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TI-2026-86425 Aliases CVE-2026-121491GHSA-qr57-vj96-mp6j

Code injection in Fiber Admin WordPress plugin enables remote code execution

Priority MEDIUM 40CWE-94Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-94.

Summary

The Fiber Admin WordPress plugin from 3.1.0 before 4.0.1 does not validate or escape a request header before writing it into a PHP file it regenerates, which is a code injection flaw (CWE-94). An unauthenticated remote attacker can execute arbitrary code when the custom database error page is enabled and the attacker wins a race against an administrator saving the plugin settings. A public exploit is linked in the references.

Written with Claude Haiku 5.5 from the sources below · 2026-11-07

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00224 13th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by the CNA
Fix Fixed Fiber Admin (Unknown): 4.0.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
UnknownFiber Admin3.1.0 to before 4.0.14.0.1Patch availableCNA
  • Fiber Admin VendorUnknown Affected 3.1.0 to before 4.0.1 Fixed in 4.0.1 Patch available CNA

Remediation

Update Fiber Admin to version 4.0.1.

Written with Claude Haiku 5.5 from the sources below · 2026-11-07

  • Fix · CNA Fiber Admin (Unknown) Fixed in 4.0.1

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    Fiber Admin 4.0.1

    2 records Highest priority Priority MEDIUM 1 MEDIUM, 1 LOW

    Other records, highest priority first

    • TI-2026-86426 Missing authorization in Fiber Admin lets attackers reorder postsPriority LOW 29
    Show all 2 records →

Timeline

  1. 2026-11-07 Threatist record created from CVE-2026-121491
  2. 2026-11-07 Alias added: GHSA-qr57-vj96-mp6j
  3. 2026-11-07 CVSS score added · CISA ADP
  4. 2026-11-07 Weakness changed · CISA ADP
  5. 2026-11-07 CISA SSVC decision points changed
  6. 2026-11-08 Priority changed: LOW → MEDIUM

References

Exploit 1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences