Shibboleth WordPress Plugin Fails to Verify Identity Headers

The Shibboleth WordPress plugin before 2.5.4 does not fail closed when its HTTP header identity mode is enabled without an anti-spoofing key, treating any request that carries identity headers as an authenticated session without verifying them. On a deployment where untrusted client headers reach the application, an unauthenticated attacker can log in with forged identity headers and, when automatic account creation and the default administrator role mapping are enabled, create and sign in as a new administrator. Exploitation requires the non-default HTTP header attribute mode, an empty or absent spoof key, automatic account creation enabled, and a deployment that does not strip untrusted client headers before they reach the application.

Casky was already ahead

This CVE exploits attack patterns that Casky's 283matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

The Shibboleth WordPress plugin before version 2.5.4 contains a critical authentication bypass vulnerability (CWE-287) in its HTTP header identity mode. When enabled without an anti-spoofing key, the plugin treats any request carrying identity headers as an authenticated session without validation, allowing unauthenticated attackers to forge credentials. Organizations running vulnerable versions are at immediate risk, particularly those with automatic account creation enabled—attackers can create admin accounts and gain full WordPress access. This affects enterprises relying on Shibboleth for federated authentication, especially where untrusted client headers can reach the application through misconfigured proxies or load balancers.

Casky's 283 mapped security skills use Claude AI with extended reasoning to detect the attack patterns underlying this vulnerability across MITRE ATT&CK techniques TA0004 (Privilege Escalation) and TA0006 (Credential Access). Practitioners using Casky would see detections for suspicious authentication patterns: requests with forged identity headers bypassing normal login flows, unexpected privilege escalation to administrator roles without standard authentication, and account creation anomalies tied to unauthenticated sessions. The platform's reasoning engine correlates header injection attempts (credential forgery) with subsequent unauthorized administrative actions, surfacing behavioral indicators that distinguish legitimate federated auth from exploitation attempts—enabling security teams to identify compromised deployments before admin accounts are weaponized.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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283 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-12281.

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

Access with Stolen Session Cookie

identity access management · low

Run

MITRE ATT&CK Techniques

TA0004 TA0006

Investigate the attack patterns behind CVE-2026-12281

Casky has 283 skills that investigate the attack patterns behind CVE-2026-12281. Run one and get CVSS-scored findings in 3 minutes.

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