CVE-2026-121491
Fiber Admin 3.1.0 - 4.0.0 - Unauthenticated RCE via Host Header
- Critical 9.0
- A public exploit reference is listed
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.
Key facts
- Published
- 7 Nov 2026
- Last changed
- 7 Nov 2026
- Assigned by
- WPScan
- EPSS
- 0.395% likely to be exploited in the next 30 days, higher than 34.25% of CVEs (scores for 15 Nov 2026)
- SSVC (CISA)
- Exploitation: none; Automatable: no; Technical impact: total
Severity scores
Each score is shown as its source gave it. They are not averaged or merged.
- 9.0CVSS 3.1, Criticalfrom CISA (ADP container)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Historical context and remediation
This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.
No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.
No explicit remediation statement is available on this page yet. Consult the original record and vendor references before choosing a fix.
Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.
Affected products
| Vendor | Product | Versions |
|---|---|---|
| Unknown | Fiber Admin |
|
Timeline
- 7 Nov 2026 Published