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Back to active CVEs
Unknown severity · Source severity not reportedCVE-2026-121491

Fiber Admin 3.1.0 - 4.0.0 - Unauthenticated RCE via Host HeaderCVE-2026-121491

Answer in brief

CVE-2026-121491 records a Unknown severity vulnerability in Fiber Admin 3.1.0 - 4.0.0 - Unauthenticated RCE via Host Header. The current sources do not mark it as known exploited. The current feed maps Unknown/Fiber Admin (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Nov 7, 2026Updated Nov 7, 2026Source checked Nov 7, 2026First seen by HOL Nov 7, 2026Material review Nov 7, 2026
Upstream Advisory

Key facts

Risk
Unknown severitySource severity not reported
Exploitation
Not marked as known exploited
Affected software
1 mapped package or product
Fix availability
Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Unknown/Fiber Admin (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Unknown/Fiber Admingeneric>=3.1.0 <4.0.14.0.1

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Unknown/Fiber Admin.
  2. 2Review the reported fix. Update Unknown/Fiber Admin to 4.0.1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Nov 7, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Nov 7, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Nov 7, 2026

Sources and claim methodology

  • Source referencewpscan.com
Upstream source 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.

Quoted source text, attributed separately from HOL analysis.

Related CVEs

  • Fiber Admin < 4.0.1 - Unauthenticated Arbitrary Post and Term Order Modification via fiad_cpo_update and fiad_cpo_tax_updateSame unknown/fiber admin package
  • Quiz and Survey Master (QSM) <= 11.2.7 - Unauthenticated Arbitrary Shortcode Execution via 'qsm_unique_key' ParameterAlso CWE-94

Record context

Vulnerability class
RCE
EPSS
Not reported
CWE IDs
CWE-94
Source
CVE List V5
Source checked
Nov 7, 2026
References
1 linked source
Open source record