What is CVE-2026-121491?

CVE-2026-121491 is a critical-severity vulnerability in Fiber Admin, classified under Code Injection. CVSS score: 9.0/10. Published 2026-11-07.

How severe is CVE-2026-121491?

Critical severity. CVSS v3 base score is 9.0 out of 10.

RCE in Fiber Admin

CVE-2026-121491

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.

Vulnerability class: RCE (Remote Code Execution)

Published 2026-11-07 · last modified 2026-11-07.

CVSS v3 metric

CVSS v3 base score 9.0 (Critical). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Fiber Admin

Weakness classification (CWE)

CWE-94 — Code Injection

References

wpscan.com/vulnerability/42b9773d-9c69-4435-be20-ae86f52b4608/ (technical-description, exploit, vdb-entry)

Frequently asked questions

What is CVE-2026-121491?: CVE-2026-121491 is a critical-severity vulnerability in Fiber Admin, classified under Code Injection. CVSS score: 9.0/10. Published 2026-11-07.
How severe is CVE-2026-121491?: Critical severity. CVSS v3 base score is 9.0 out of 10.