CVE-2026-42674: Advanced Access Manager Authentication Bypass via URL Encoding

Technical summary

CVE-2026-42674 is an authentication bypass vulnerability in the Advanced Access Manager plugin stemming from improper handling of URL-encoded input (CWE-290: Improper Input Validation). The vulnerability allows an unauthenticated attacker to spoof authentication by manipulating URL encoding in requests, bypassing the plugin's access control mechanisms. The attack requires no privileges, user interaction, or special network conditions—only network-level access to the target system. The vulnerability affects all versions of AAM from an unspecified baseline through version 7.1.0.

Business impact

Successful exploitation enables complete circumvention of the AAM plugin's access control layer, allowing unauthorized actors to access resources, functionality, or data that should be protected by authentication. This represents a direct threat to confidentiality and integrity depending on what the compromised access enables. Organizations relying on AAM as a primary access control mechanism could face unauthorized data access, privilege escalation within the application, or lateral movement to downstream systems.

Affected systems

Advanced Access Manager plugin versions up to and including 7.1.0 are affected. Organizations using AAM to enforce authentication and authorization policies should assume all instances at or below version 7.1.0 are vulnerable unless patched. The plugin's scope of impact depends on its deployment context—web applications, WordPress sites, or other platforms using AAM for access control are all at risk if running vulnerable versions.

Exploitability

This vulnerability is readily exploitable by an unauthenticated attacker with only network access. The attack vector is network-based, requires no elevated privileges or user interaction, and relies on a straightforward manipulation of URL encoding. The low complexity of the attack combined with the absence of prerequisites makes this a practical threat in most deployment scenarios. Organizations should prioritize assessment and patching urgently.

Remediation

Upgrade the Advanced Access Manager plugin to a patched version beyond 7.1.0. Verify the specific patched version against the official AAM vendor advisory, as the source data does not specify the remediation version. Organizations unable to upgrade immediately should implement compensating controls such as network-level access restrictions, rate limiting, or supplementary authentication mechanisms to reduce exposure.

Patch guidance

Consult the official Advanced Access Manager release notes and security advisory to identify the minimum patched version that remediates CVE-2026-42674. Verify compatibility with your application version before deploying. Test the patch in a non-production environment to ensure no functional regressions. Once validated, prioritize deployment across all instances running version 7.1.0 or earlier. Monitor vendor communications for any updates or additional context.

Detection guidance

Monitor for suspicious URL-encoded patterns in access requests targeting the AAM plugin, particularly those attempting to bypass authentication checks. Look for HTTP requests containing unusual or excessive URL encoding sequences in query strings or POST bodies. Implement Web Application Firewall (WAF) rules to detect and block attempts to exploit URL encoding-based spoofing. Review access logs for authentication bypass attempts—look for successful resource access from requests lacking valid authentication tokens or sessions. Enable detailed logging on the AAM plugin if available.

Why prioritize this

This vulnerability merits immediate attention due to its high CVSS score (7.5), authentication bypass nature, and zero prerequisites for exploitation. An unauthenticated attacker can trigger the vulnerability over the network without user interaction. The impact on integrity (score of H) combined with the ease of execution makes this a critical priority for any organization relying on AAM for access control.

Risk score, explained

The CVSS 3.1 score of 7.5 (HIGH) reflects a network-accessible authentication bypass with high integrity impact. The vector AV:N/AC:L/PR:N/UI:N indicates network accessibility, low attack complexity, no privilege requirement, and no user interaction—all factors reducing barriers to exploitation. While confidentiality is not directly compromised by the flaw itself, the authentication bypass enables downstream unauthorized access to protected data and functionality. The integrity impact is marked as high because attackers can modify or access resources they should not be permitted to touch.

Frequently asked questions