CVE-2026-121491 — CRITICAL (9.0)

Vulnerability Description

The Fiber Admin WordPress plugin before 4.0.1 does not validate or escape a request header before writing it into a PHP file it regenerates on an unprotected admin hook, allowing unauthenticated attackers to execute arbitrary code when its custom database error page is enabled and they win a race against an administrator saving its settings.

CVSS Score

9.0

CRITICAL

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

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

CHANGED

Confidentiality

HIGH

Integrity

HIGH

Availability

HIGH

Related Weaknesses (CWE)

CWE-94

References

https://wpscan.com/vulnerability/42b9773d-9c69-4435-be20-ae86f52b4608/

FAQ

What is CVE-2026-121491?

CVE-2026-121491 is a vulnerability with a CVSS score of 9.0 (CRITICAL). The Fiber Admin WordPress plugin before 4.0.1 does not validate or escape a request header before writing it into a PHP file it regenerates on an unprotected admin hook, allowing unauthenticated attac...

How severe is CVE-2026-121491?

CVE-2026-121491 has been rated CRITICAL with a CVSS base score of 9.0/10. This is considered a critical vulnerability requiring immediate attention.

Is there a patch for CVE-2026-121491?

Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.