CVE-2026-61812
Received
Received - Intake
HTML Entity Decode Bypass in ModSecurity
Vulnerability report for CVE-2026-61812, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-11-09
Last updated on: 2026-11-09
Assigner: GitHub, Inc.
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-172 | The product does not properly encode or decode the data, resulting in unexpected values. |
| CWE-180 | The product validates input before it is canonicalized, which prevents the product from detecting data that becomes invalid after the canonicalization step. |
