Description
ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 2.9.15 and 3.0.17, t:htmlEntityDecode recognizes only a small subset of named HTML entities, so rules that depend on the transformation can inspect different bytes than a browser or backend. Attackers can encode ASCII separators and operators with unhandled entity names, including aliases, to bypass rules that depend on the transformation. The v3 decoder also accepts prefix matches instead of requiring an exact entity-token length, which can transform invalid longer names into different bytes. This issue is fixed in versions 2.9.15 and 3.0.17.
Published: 2026-11-09
Score: 6.3 Medium
EPSS: n/a
KEV: No
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History

Mon, 09 Nov 2026 21:45:00 +0000

Type Values Removed Values Added
Description ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 2.9.15 and 3.0.17, t:htmlEntityDecode recognizes only a small subset of named HTML entities, so rules that depend on the transformation can inspect different bytes than a browser or backend. Attackers can encode ASCII separators and operators with unhandled entity names, including aliases, to bypass rules that depend on the transformation. The v3 decoder also accepts prefix matches instead of requiring an exact entity-token length, which can transform invalid longer names into different bytes. This issue is fixed in versions 2.9.15 and 3.0.17.
Title ModSecurity: HTML decoder missing entities, leading to evasion
Weaknesses CWE-172
CWE-180
References
Metrics cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N'}

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-11-09T21:37:05.788Z

Reserved: 2026-07-10T20:17:57.991Z

Link: CVE-2026-61812

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses