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No exploitation reportedAwaiting NVD analysis

CVE-2026-73856

ModSecurity: Response Body Inspection Bypass

No exploitation reported by the sources we read.

  • Published2026-11-05
  • WeaknessCWE-178

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2026-11-0515:50CVE publishedCNA

Versions per branch

Products declared by the CNA1 product

As GitHub_M, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • owasp-modsecurity ModSecurity
    Affected
    • = >= 3.0.0, < 3.0.17no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-05

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • modsecurityUbuntu:26.10all versions · no fixed version listed
  • modsecurityUbuntu:26.04:LTSall versions · no fixed version listed
  • modsecurityUbuntu:24.04:LTSall versions · no fixed version listed
  • modsecurityUbuntu:22.04:LTSall versions · no fixed version listed
  • modsecurityUbuntu:20.04:LTSall versions · no fixed version listed
  • modsecurityDebian:14all versions · no fixed version listed
  • modsecurityDebian:13all versions · no fixed version listed
  • modsecurityDebian:12all versions · no fixed version listed

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Metasploit modules
none listed
Metasploit Framework

Sources

  • CNACVSS 3.18.62026-11-05
  • CNAweakness (CWE)CWE-1782026-11-05
  • NVDweakness (CWE)CWE-178read 2026-11-05
  • OSVaffected packages—

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Published
2026-11-05
Last Modified
2026-11-05
NVD status
Received

Frequently asked questions

What is CVE-2026-73856?

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.

Is CVE-2026-73856 actively exploited?

Active exploitation of CVE-2026-73856 has not been confirmed.

What is the CVSS score for CVE-2026-73856?

CVE-2026-73856 has a CVSS v3 base score of 8.6 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N.

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