CVE-2026-121491criticalCWE-94

CVE-2026-121491: critical vulnerability in Fiber Admin

Fiber Admin 3.1.0 - 4.0.0 - Unauthenticated RCE via Host Header

Published

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48Vexday Risk Score

No sign of exploitation. It has a public proof of concept.

ssvc Attendcvss 9epss 0.4%
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:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Affected products
Unknown · Fiber Admin
⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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In the same product, most dangerous first.

CVE-2026-121492MEDIUMFiber Admin < 4.0.1 - Unauthenticated Arbitrary Post and Term Order Modification via fiad_cpo_update and fiad_cpo_tax_updateEPSS 0.2%