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20Track

Fiber Admin 3.1.0 - 4.0.0 - Unauthenticated RCE via Host Header

Fiber Admin · CVE-2026-121491 ETK-2026-3807 EUVD-2026-118943 GHSA-QR57-VJ96-MP6J
0 news outlets0 CERTs and agencies1 research labs

Assessment: Track

SSVC decision points: exploitation none, automatable no, technical impact total, deployment low.

What is it?

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.

Evidence

Technical advisories1Detailed write-ups from security research teams

Exploitation

  • Exploit code published (not verified by us)
  • Exploited in the wild (confirmed by a source)
  • Listed as known exploited (CISA KEV)
CVSS
9.0
EPSS
0.2%
First seen
1 d ago
Status
confirmed