# CVE-2026-61812: ModSecurity: HTML decoder missing entities, leading to evasion

Status: published. Published: 2026-11-09. Updated: 2026-11-09.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- owasp-modsecurity / ModSecurity: < 2.9.15 (affected); >= 3.0.0, < 3.0.17 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 4.0: 6.3 (medium); 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; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-172, CWE-180

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-cxqf-vgrr-xxrv (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/owasp-modsecurity/ModSecurity/commit/6353be7b09ff222d29a7491c26307d293b00d56f (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/owasp-modsecurity/ModSecurity/commit/77be8039d734d36ec291d8fbda9e69326ae44755 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v2.9.15 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.17 (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-61812; retrieved 2026-11-09; source updated 2026-11-09

Revision: d38c4bbeaa46cf734337c23eea07707fc265a6e84be21b0b41ec906defe18a4e

Canonical: https://y2.dev/cve/CVE-2026-61812

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