
October 2026 Security Update Review
The October 2026 security update review covers Microsoft's record-breaking Patch Tuesday, actively exploited Windows vulnerabilities, critical CVEs, and patch management priorities.
October 14, 2026 - Blog
Authored By Packetlabs

Infrastructure security is a fundamental component of an organization's cybersecurity strategy. Vulnerabilities in operating systems, authentication protocols, directory services, and network configurations can give attackers opportunities to gain unauthorized access, escalate privileges, steal credentials, and move laterally across corporate networks.
The Open Worldwide Application Security Project (OWASP) maintains the OWASP Top 10 to highlight critical risks to web applications. However, application security is only one part of the broader cybersecurity landscape. Organizations must also address infrastructure vulnerabilities that affect servers, endpoints, identity systems, and internal networks.
At Packetlabs, we have identified 10 critical infrastructure security risks that organizations should prioritize when assessing and hardening their environments. This list includes both software vulnerabilities and common attack techniques that exploit insecure configurations, weak authentication controls, and inadequate credential management.
Not every item represents a single software vulnerability with a corresponding patch. Some, such as NTLM relay attacks and Kerberoasting, are attack techniques that can succeed when an environment lacks appropriate security controls. Others, such as PrintNightmare, involve specific vulnerabilities that require security updates and configuration changes.
Organizations should prioritize remediation based on exploitability, business impact, exposure, and the privileges an attacker could obtain. Applying patches remains essential, but patch management must work alongside secure configuration, identity protection, monitoring, and regular security testing.
Recent cybersecurity research reinforces the importance of proactive vulnerability management.
According to Verizon's 2025 Data Breach Investigations Report, exploitation of vulnerabilities accounted for 20% of breaches involving a known initial access vector, representing a 34% increase compared with the previous report. Credential abuse accounted for 22%, making it another leading initial access method. Verizon's analysis covered more than 22,000 security incidents, including 12,195 confirmed data breaches.
The financial consequences can also be substantial. IBM's 2026 Cost of a Data Breach Report put the global average cost of a data breach at $4.99 million. The report also found that one in four malicious breaches was AI-enabled, with these incidents costing an average of $6 million.
These findings highlight why organizations should treat infrastructure security as an ongoing business priority rather than a periodic IT maintenance task.
Remote and hybrid work environments have expanded the range of systems organizations must protect. Employees may access corporate resources through VPNs, remote management tools, cloud services, and devices operating outside traditional corporate networks.
These environments introduce additional challenges for patch management, authentication, and endpoint security. Remote systems may miss updates, retain outdated software, or rely on legacy authentication protocols that attackers can exploit.
The problem extends beyond remote work. Large organizations often operate complex environments containing legacy applications, third-party integrations, domain controllers, file servers, and specialized business systems. Dependencies and operational requirements can make it difficult to apply updates quickly.
Security teams must therefore prioritize remediation based on risk rather than treating every vulnerability equally.
The Cybersecurity and Infrastructure Security Agency (CISA) maintains its Known Exploited Vulnerabilities (KEV) Catalog to help organizations identify vulnerabilities that attackers are actively exploiting. Organizations should incorporate this catalog into their vulnerability management processes and prioritize applicable vulnerabilities accordingly.
The following 10 infrastructure security risks illustrate where organizations should focus their attention.
Microsoft Active Directory Certificate Services (AD CS) provides public key infrastructure capabilities within Windows environments. Organizations use it to issue and manage digital certificates for authentication, encryption, and other security functions.
Although AD CS is not installed by default in every Windows environment, organizations that deploy it can introduce significant security risks through misconfigured certificate authorities, certificate templates, enrollment permissions, and authentication settings.
Research published by Will Schroeder and Lee Christensen in 2021, titled Certified Pre-Owned, demonstrated how weaknesses in AD CS configurations could allow attackers with limited privileges to escalate access within Active Directory environments.
Depending on the configuration, an attacker may be able to obtain a certificate that supports authentication as a privileged user. Successful exploitation can lead to domain compromise.
Organizations should review their AD CS deployments and:
Audit certificate templates, enrollment permissions, and access control lists.
Restrict enrollment privileges to users and groups with a legitimate business requirement.
Review certificate configurations for unsafe subject name settings and authentication purposes.
Harden certificate authority servers and restrict administrative access.
Evaluate NTLM authentication exposure and implement appropriate signing and channel-binding protections.
Enable certificate authority auditing and monitor suspicious certificate enrollment and template modifications.
Relevant Windows security events include certificate request and issuance events, such as Event IDs 4886 and 4887, and certificate template modification events, such as Event ID 4899. Monitoring should be tailored to the organization's Windows versions, logging configuration, and detection requirements.
AD CS security requires more than applying operating system updates. Organizations must also address insecure certificate configurations and permissions that can create privilege escalation opportunities.
PrintNightmare refers to vulnerabilities associated with the Windows Print Spooler service, particularly CVE-2021-34527 and CVE-2021-1675.
The Print Spooler manages print jobs and related operations. Depending on the vulnerability and system configuration, exploitation can allow an attacker to execute code with elevated privileges or compromise a vulnerable system.
The potential impact is particularly serious when the service is enabled on sensitive systems, including domain controllers, where compromise can threaten the security of the wider Active Directory environment.
PrintNightmare is a software vulnerability, not a domain-fronting technique. Domain fronting is a separate technique involving the use of intermediary infrastructure, such as content delivery networks, to obscure the destination of command-and-control traffic.
Organizations should:
Apply the relevant Microsoft security updates.
Disable the Print Spooler service on systems that do not require printing.
Review and restrict printer driver installation permissions.
Restrict remote printing where it is unnecessary.
Monitor suspicious printer driver installations and unexpected Print Spooler activity.
Verify that domain controllers and other critical servers have appropriate security configurations.
Disabling unnecessary services can reduce the attack surface, but organizations should assess operational requirements before making configuration changes.
For further guidance, consult Microsoft's security information for CVE-2021-34527.
NT LAN Manager (NTLM) is a legacy authentication protocol used in some Windows environments. NTLMv1 is substantially weaker than modern authentication alternatives and exposes organizations to risks involving credential cracking and authentication attacks.
In a downgrade attack, an attacker attempts to cause a system to use a weaker authentication method than intended. NTLMv1 challenge-response data can be susceptible to offline password-cracking attacks, particularly when users have weak passwords.
Organizations that retain legacy applications or older systems may continue to support NTLMv1 for compatibility reasons. However, leaving the protocol enabled can undermine broader identity security controls.
Organizations should:
Identify systems and applications that still rely on NTLMv1.
Disable NTLMv1 where operationally feasible.
Use Group Policy to enforce stronger authentication settings.
Prefer Kerberos authentication when supported.
Investigate legacy dependencies before removing compatibility settings.
Monitor authentication logs for unexpected NTLM use and downgrade indicators.
Disabling NTLMv1 should form part of a broader effort to reduce reliance on legacy authentication protocols. Organizations should also evaluate whether NTLM can be restricted further without disrupting essential business operations.
NTLM relay attacks exploit the way NTLM authentication exchanges can be forwarded between systems.
Unlike pass-the-hash attacks, NTLM relay does not inherently require an attacker to obtain a user's password hash and reuse it to authenticate. Instead, the attacker intercepts or induces an authentication exchange and relays the live challenge-response interaction to another service that accepts it.
If the destination service lacks appropriate protections, the attacker may authenticate as the legitimate user without knowing the user's password.
Successful relaying can result in unauthorized access, privilege escalation, lateral movement, or compromise of sensitive services.
SMB and LDAP are important targets in Active Directory environments.
Server Message Block (SMB) supports file sharing and other network services. If SMB signing is not appropriately enforced, an attacker may be able to relay authentication to a vulnerable SMB service.
Lightweight Directory Access Protocol (LDAP) supports directory operations. Inadequately protected LDAP services may also be vulnerable to authentication relaying, depending on the configuration and attack path.
Attackers may additionally use authentication coercion techniques to induce a Windows system to authenticate to an attacker-controlled endpoint. Tools associated with techniques such as PrinterBug and PetitPotam have demonstrated how certain Windows services and remote procedure call interfaces can be abused for this purpose.
Organizations should:
Enforce SMB signing on supported clients and servers.
Require LDAP signing and channel binding where appropriate.
Implement Extended Protection for Authentication (EPA) on supported services.
Restrict NTLM authentication and migrate to Kerberos where feasible.
Review systems for authentication coercion exposure.
Limit privileged account logons and unnecessary administrative access.
Monitor unusual authentication patterns and unexpected access to directory services.
Disabling NTLM entirely may not be immediately practical in every environment. A phased approach should identify dependencies, strengthen existing protections, and progressively reduce reliance on NTLM.
Link-Local Multicast Name Resolution (LLMNR) and NetBIOS Name Service (NBT-NS) are legacy Windows name-resolution mechanisms. They can allow systems to resolve hostnames when standard DNS resolution fails.
Dynamic Host Configuration Protocol for IPv6 (DHCPv6) provides IPv6 configuration information to network clients. In certain environments, weaknesses in IPv6 configuration and network controls can allow attackers to interfere with network traffic or influence client behavior.
These protocols and services can introduce opportunities for attackers to redirect name-resolution requests, capture authentication exchanges, or facilitate NTLM relay attacks.
For example, an attacker with access to an internal network may respond to a name-resolution request before the legitimate system does. If the victim system attempts to authenticate to the attacker's machine, the attacker may be able to relay the authentication exchange to another service or attempt to crack captured authentication material offline.
Related techniques may also involve Web Proxy Auto-Discovery (WPAD), multicast DNS (mDNS), or weaknesses in Active Directory-integrated DNS.
Organizations should:
Disable LLMNR and NBT-NS where they are not required.
Review DHCPv6 and IPv6 configurations for weaknesses.
Restrict unnecessary network services and protocols.
Disable automatic proxy discovery where it is not needed.
Enforce SMB signing and other appropriate authentication protections.
Prefer Kerberos over NTLM where possible.
Monitor suspicious name-resolution responses and authentication attempts.
Disabling individual protocols is not always sufficient. Organizations should assess their entire network configuration to identify alternative poisoning and relay attack paths.
Strong passwords can reduce the effectiveness of offline cracking, but they do not independently prevent authentication relay attacks.
Kerberoasting is an attack technique that targets service accounts in Microsoft Active Directory environments.
In Kerberos authentication, services may be associated with accounts that have a service principal name (SPN). A domain user can request a service ticket for an SPN, and the ticket contains a portion encrypted using a key derived from the associated account's password.
An attacker with legitimate domain access may request service tickets and attempt to crack their encrypted components offline. If the password is weak, outdated, or predictable, the attacker may recover it and use the service account's privileges to access additional systems.
Kerberoasting is particularly concerning when service accounts have excessive permissions or use passwords that are not sufficiently strong.
Because requesting service tickets can be legitimate activity, detecting malicious behavior may require additional context.
Organizations should:
Use long, unique, randomly generated passwords for service accounts.
Prefer group Managed Service Accounts (gMSAs) where supported.
Restrict service account privileges according to the principle of least privilege.
Inventory accounts with SPNs and remove unnecessary configurations.
Use strong Kerberos encryption settings supported by the environment.
Monitor unusual volumes or patterns of service ticket requests.
Investigate service accounts that have excessive privileges or outdated credentials.
Organizations should also review service account ownership and establish processes for rotating credentials when required.
Reducing unnecessary privileges limits the impact of a compromised service account, even if an attacker successfully recovers its password.
Local administrator accounts can provide extensive control over individual Windows systems. However, reusing the same password across multiple machines creates a significant lateral movement risk.
If an attacker compromises a local administrator account on one workstation or server, they may attempt to use the same credentials on other systems.
When password reuse is widespread, a single compromised endpoint can provide access to multiple machines. The risk increases when administrative credentials are exposed on systems that also handle sensitive information or privileged user sessions.
Local administrator password reuse is not necessarily a software vulnerability. It is an identity and configuration weakness that can allow an initial compromise to spread.
Organizations should:
Assign unique local administrator passwords to individual systems.
Implement Microsoft Local Administrator Password Solution (Windows LAPS).
Rotate local administrator passwords according to an appropriate security policy.
Restrict administrative privileges and remove unnecessary local administrators.
Monitor suspicious logons and attempts to reuse credentials across endpoints.
Prevent privileged domain accounts from logging on to untrusted workstations.
Review endpoint security policies to limit credential theft and lateral movement.
Windows LAPS can help organizations manage and rotate local administrator passwords automatically. Administrators should configure appropriate access controls for password retrieval and ensure that the solution is deployed and monitored correctly.
Organizations should also establish separate administrative accounts for different security tiers. This reduces the likelihood that a compromised workstation will expose credentials that provide access to critical servers or domain controllers.
CVE-2021-42278 and CVE-2021-42287 are vulnerabilities associated with Active Directory security account management and Kerberos authentication.
When combined, these vulnerabilities can allow an attacker with a low-privileged domain account to impersonate a domain controller under vulnerable conditions, potentially escalating privileges and compromising the domain.
The attack involves weaknesses in how computer account names and Kerberos service tickets were handled. An attacker could manipulate a computer account's sAMAccountName and exploit the way the domain controller resolved account identities during authentication.
This attack path became widely known as the noPac vulnerability chain.
Successful exploitation could result in domain-level privilege escalation, making these vulnerabilities particularly important for organizations that operate Active Directory.
Organizations should:
Install the applicable Microsoft security updates.
Verify that domain controllers have the necessary security updates and enforcement changes.
Review computer account creation permissions.
Assess the MachineAccountQuota setting and restrict unnecessary machine account creation.
Monitor unusual computer account modifications and suspicious Kerberos service ticket activity.
Investigate unexpected privilege escalation indicators in domain controller logs.
Microsoft released security updates to address these vulnerabilities. Organizations should follow Microsoft's guidance to verify that the relevant patches and subsequent enforcement requirements have been applied.
Setting MachineAccountQuota to zero may reduce the ability of ordinary domain users to create new computer accounts. However, this is not a substitute for patching and may affect legitimate workflows that depend on user-created computer accounts.
Organizations should validate their Active Directory configurations rather than assuming that one configuration change eliminates the entire attack path.
Sensitive information is sometimes stored in locations that are accessible to more users than necessary. This may include shared folders, scripts, configuration files, backups, deployment tools, and administrative documents.
When credentials or other sensitive information are stored without sufficient protection, attackers may be able to obtain them after compromising an account with relatively limited privileges.
Examples include:
Passwords embedded in scripts.
Credentials stored in configuration files.
Service account secrets in shared folders.
Database connection strings containing passwords.
Unprotected backups containing sensitive information.
Private keys or other authentication material stored with insufficient access controls.
The impact depends on the information exposed. A single password may provide access to a business application, while a privileged service account credential could enable extensive lateral movement or domain compromise.
Insecure data storage is often a preventable risk because it can be addressed through access controls, secure development practices, and better credential management.
Organizations should:
Apply the principle of least privilege to files, folders, and shared resources.
Remove plaintext passwords and other secrets from scripts and configuration files.
Use an enterprise password manager or secrets management platform.
Restrict access to backups and administrative repositories.
Scan repositories and file shares for exposed credentials.
Rotate credentials that may have been exposed.
Encrypt sensitive data where appropriate.
Establish secure processes for storing, sharing, and retiring secrets.
Developers and system administrators should avoid embedding reusable credentials in scripts. Where possible, applications should retrieve secrets securely at runtime through an approved secrets management solution.
Organizations should also assess whether sensitive files are accessible to ordinary domain users who do not need them to perform their jobs.
Restricting access is particularly important for backup repositories, which may contain copies of sensitive production data and configuration information.
Windows systems maintain authentication information to support legitimate sign-in and access operations. Depending on the authentication method and system configuration, sensitive credential material may be stored in memory or in credential stores.
The Local Security Authority Subsystem Service (LSASS) is a Windows process responsible for important authentication and security functions. Attackers who obtain sufficient privileges may attempt to access LSASS memory to extract credential material or other authentication secrets.
However, not all credentials are stored in plaintext, and cached credentials should not be treated as synonymous with cleartext passwords.
The ability to recover particular credentials depends on the Windows version, authentication method, security configuration, and privileges available to the attacker.
For example, Microsoft disabled WDigest credential caching by default beginning with Windows 8.1 and Windows Server 2012 R2. On these and later supported systems, cleartext password caching through this mechanism is disabled by default unless the configuration is changed.
Task Manager can be used to create a process dump under certain circumstances, but it does not automatically expose cleartext credentials. Access to LSASS memory is also subject to operating system protections and security controls.
Organizations should:
Enable Credential Guard on supported systems where appropriate.
Configure LSASS protection according to Microsoft's security guidance.
Keep Windows systems updated and securely configured.
Prevent privileged accounts from logging on to lower-trust endpoints.
Separate administrative accounts according to security tiers.
Apply least-privilege principles to local and domain accounts.
Use endpoint detection and response (EDR) tools to detect suspicious credential access.
Investigate unauthorized attempts to access LSASS memory or credential stores.
Credential Guard uses virtualization-based security to help protect certain secrets from unauthorized access. Its availability and effectiveness depend on hardware, operating system, configuration, and compatibility requirements.
Credential theft prevention should also address the circumstances that allow attackers to obtain administrative access in the first place.
Organizations should avoid using domain administrator accounts for routine workstation administration. Separating privileged accounts and limiting where they can sign in reduces the potential exposure of high-value credentials.
Addressing infrastructure vulnerabilities requires a structured vulnerability management program. Organizations may identify hundreds or thousands of vulnerabilities across their systems, and treating every finding as equally urgent can make effective remediation difficult.
A risk-based approach helps security teams focus on weaknesses that pose the greatest threat to the organization.
Start by identifying vulnerabilities that are known to be exploited in real-world attacks.
CISA's Known Exploited Vulnerabilities Catalog provides a useful source for identifying such vulnerabilities. Organizations should assess whether listed vulnerabilities affect their assets and prioritize remediation in accordance with their risk and applicable requirements.
Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
A vulnerability affecting an internet-facing system may require more urgent attention than a similar vulnerability on an isolated device.
However, internal systems should not automatically receive lower priority. A compromised workstation, identity server, or internal application may provide a pathway to critical business systems.
Prioritization should account for exposure, business function, data sensitivity, and the consequences of compromise.
Security teams should assess whether a vulnerability allows remote code execution, privilege escalation, authentication bypass, or access to sensitive information.
They should also consider the attacker's likely starting point and the privileges required for exploitation.
A vulnerability that allows unauthenticated remote access to a critical system may present a different level of risk than one that requires extensive privileges and local access.
Installing a patch or changing a configuration is not the end of the remediation process.
Organizations should verify that updates were successfully applied, affected services were restarted where necessary, and the vulnerability is no longer exploitable.
Follow-up vulnerability scans and penetration tests can help identify missed systems, incomplete remediation, and alternative attack paths.
Vulnerability scanning and patch management are important, but they do not provide a complete assessment of infrastructure security.
A vulnerability scan can identify known weaknesses and outdated software. A penetration test goes further by evaluating how weaknesses can be combined and exploited within an authorized assessment.
For example, a penetration test may determine whether an exposed credential can provide access to an internal workstation, whether that workstation permits lateral movement, and whether the resulting access can be escalated to a privileged account.
This approach helps organizations understand the practical consequences of infrastructure weaknesses rather than relying solely on individual vulnerability ratings.
Penetration testing can also evaluate:
Active Directory security and privilege escalation paths.
Authentication and authorization controls.
Credential exposure and password reuse.
Network segmentation and lateral movement.
Server hardening and patch management.
Access to sensitive information and backups.
Detection and response capabilities.
The results can help security teams prioritize remediation based on demonstrated risk and validate whether security controls are working as intended.
Infrastructure security requires continuous attention to vulnerabilities, identity controls, system configurations, and emerging attack techniques.
The 10 risks outlined in this article demonstrate how attackers can exploit weaknesses in Active Directory, legacy authentication protocols, credential management, and Windows services to gain unauthorized access and move through corporate networks.
Although patching is essential, effective infrastructure security requires a broader strategy that includes secure configurations, least-privilege access, credential protection, monitoring, and regular security testing.
Organizations should prioritize known exploited vulnerabilities, assess the business impact of security findings, and verify that remediation measures are effective.
At Packetlabs, we specialize in penetration testing and application security. Our team helps organizations identify exploitable weaknesses, understand their potential impact, and strengthen their security posture through actionable testing and remediation guidance.
If your organization is concerned about infrastructure vulnerabilities, a penetration test can help identify weaknesses before attackers exploit them.
Contact Packetlabs to discuss your security requirements and book a discovery call: https://www.packetlabs.net/
Critical infrastructure security risks include Active Directory Certificate Services misconfigurations, PrintNightmare, NTLM relay attacks, Kerberoasting, local administrator password reuse, insecure data storage, and credential theft. The most urgent issues depend on the organization's environment, exposure, and potential business impact.
Patch management addresses known software vulnerabilities that attackers may exploit to gain unauthorized access, execute code, or escalate privileges. A structured patch management program helps organizations reduce their attack surface and prioritize vulnerabilities based on exploitability, exposure, and business risk.
Organizations should establish a vulnerability scanning schedule based on their risk profile, regulatory requirements, and infrastructure complexity. Quarterly scanning can provide a baseline for many environments, while organizations with extensive or frequently changing infrastructure may benefit from weekly or continuous scanning.
Organizations should also conduct additional scans after significant infrastructure changes, security incidents, or major remediation efforts.
Vulnerability scanning identifies known weaknesses in systems, applications, and configurations. Penetration testing involves authorized attempts to exploit security weaknesses to determine whether they can be used to compromise systems or access sensitive information.
Both are valuable components of a comprehensive vulnerability management program.
Organizations can reduce NTLM relay risk by enforcing SMB signing, implementing LDAP signing and channel binding where appropriate, enabling Extended Protection for Authentication on supported services, and reducing reliance on NTLM. They should also review authentication coercion risks and monitor suspicious authentication activity.
Kerberoasting is an attack technique that targets Kerberos service tickets associated with Active Directory service accounts. Attackers can attempt to crack ticket components offline to recover weak service account passwords.
Organizations can reduce the risk by using strong, unique service account credentials, deploying group Managed Service Accounts where supported, restricting account privileges, and monitoring suspicious service ticket requests.
NTLM relay forwards an authentication exchange to another service that accepts it, potentially allowing an attacker to authenticate without knowing the user's password.
Pass-the-hash involves reusing captured password hash material in an authentication process that supports it, without recovering the original plaintext password. The techniques are distinct, although both can facilitate unauthorized access.
Penetration testing helps organizations identify exploitable weaknesses and understand how attackers might combine them to gain access, escalate privileges, or move laterally across a network. It also helps validate remediation efforts and evaluate the effectiveness of security controls.
Organizations should prioritize vulnerabilities known to be exploited in the wild, especially when they affect internet-facing systems, critical infrastructure, identity services, or sensitive business assets.
Prioritization should also account for exploitability, available mitigations, business impact, and the potential consequences of compromise. CISA's Known Exploited Vulnerabilities Catalog is one useful input into this process.
No. Vulnerability scans help identify known weaknesses, but they do not independently assess every attack path or demonstrate how vulnerabilities could be combined to compromise an environment.
Organizations should combine vulnerability scanning with patch management, secure configuration reviews, identity security controls, monitoring, and periodic penetration testing.
Speak with an Account Executive