---
id: CVE-2026-73856
title: 'ModSecurity: Response Body Inspection Bypass'
summary: >-
  ModSecurity is an open source, cross platform web application firewall (WAF)
  engine for Apache, IIS and Nginx. From 3.0.0 until 3.0.17, src/transaction.cc
  compares a response Content-Type value against SecResponseBodyMimeType entries
  cas…
severity: high
cvss: 8.6
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N'
cvssSource: cna
cwe:
  - CWE-178
vendor: owasp-modsecurity
product: ModSecurity
affected:
  - 'ModSecurity >= 3.0.0, < 3.0.17'
published: '2026-11-05'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T15:50:09.778Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-73856'
references:
  - url: >-
      https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-vmg8-j66p-vgvw
    label: >-
      https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-vmg8-j66p-vgvw
  - url: >-
      https://github.com/owasp-modsecurity/ModSecurity/commit/23ccd9202114f8313df3773f7992782fd9949c98
    label: >-
      https://github.com/owasp-modsecurity/ModSecurity/commit/23ccd9202114f8313df3773f7992782fd9949c98
  - url: 'https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.17'
    label: 'https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.17'
tags:
  - cve.org
ingestedAt: '2026-11-05T21:36:00.925Z'
---

## Overview

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 until 3.0.17, src/transaction.cc compares a response Content-Type value against SecResponseBodyMimeType entries case-sensitively. A mixed-case response media type that is semantically equivalent to a configured lowercase type can therefore be treated as unconfigured, causing ModSecurity to skip RESPONSE_BODY inspection. An unauthenticated requester can then receive response content that a phase 4 rule would otherwise block, including sensitive error or debug data. This issue is fixed in version 3.0.17.

## Affected

- `ModSecurity >= 3.0.0, < 3.0.17`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.