CVE-2026-12281: Auth Bypass (CVSS 8.1)

Description

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.

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CVSS v3.1 Score

8.1

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0023

Probability of exploitation

0.14%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-287 Improper Authentication

References

Other References

https://wpscan.com/vulnerability/8474eda4-6385-447a-9139-f57c049d1713/

Frequently Asked Questions

What is CVE-2026-12281? +

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. It has a CVSS v3.1 base score of 8.1 (HIGH).

How severe is CVE-2026-12281? +

CVE-2026-12281 has a CVSS v3.1 score of 8.1 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0023, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-12281? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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