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CVE-2026-121491 Code Injection

9.0 criticalEPSS 0.4%

Critical (9.0). EPSS 0.4% estimated probability of exploitation activity in the next 30 days.

On this page
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.

Severity

CVSS 3.1

9.0 critical
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS
0.4% estimated probability of exploitation activity in the next 30 days; 34th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
CISA's assessment (SSVC)
Exploitation: none · Automatable: no · Technical impact: total, assessed 2026-11-07. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
CWE
CWE-94 Improper Control of Generation of Code (Code Injection)
OWASP Top 10
A05:2025 Injection
Published
Modified
NVD analysis
Deferred: the NVD does not plan to analyze it
Record from
the NVD, synced

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CVE-2026-121491

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Attack patterns (CAPEC)

  • CAPEC-35 Leverage Executable Code in Non-Executable Files Likelihood: High · Severity: Very High
  • CAPEC-77 Manipulating User-Controlled Variables Likelihood: High · Severity: Very High
  • CAPEC-242 Code Injection Likelihood: High · Severity: High

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.

History

  1. The NVD deferred its analysis

Changes since this site first stored the record. The same for every record: /api/public/changes.

References

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