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No exploitation reportedAwaiting NVD analysis

CVE-2026-104269

ModSecurity: RFC 2231 `filename*` Parameter Bypasses Multipart Filename Rules on RFC-Compliant Backends (Go, Python, Node, Java)

No exploitation reported by the sources we read.

  • Published2026-11-05
  • WeaknessCWE-436

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, ModSecurity's multipart parser does not apply the RFC 2231 filename* parameter precedence used by common Go, Python, Node.js, and Java application parsers. A Content-Disposition header can provide a benign filename parameter for ModSecurity and a different encoded filename* value that the backend prefers, causing MULTIPART_FILENAME rules and the application to make security decisions on different names. Applications that use the backend-selected name for storage, extension checks, or content-type inference can therefore receive a filename that bypassed WAF inspection. PHP's native multipart parser is not affected by this discrepancy. This issue is fixed in version 3.0.17.

Timeline

dates in UTC
  1. 2026-11-0515:51CVE 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 listedand 1 other package
  • modsecurityUbuntu:26.04:LTSall versions · no fixed version listedand 1 other package
  • 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 listedand 1 other package
  • modsecurityDebian:13all versions · no fixed version listedand 1 other package
  • modsecurityDebian:12all versions · no fixed version listedand 1 other package

6 more package ranges on OSV.dev

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-4362026-11-05
  • NVDweakness (CWE)CWE-436read 2026-11-05
  • OSVaffected packages—

Technical details

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

Frequently asked questions

What is CVE-2026-104269?

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, ModSecurity's multipart parser does not apply the RFC 2231 filename* parameter precedence used by common Go, Python, Node.js, and Java application parsers. A Content-Disposition header can provide a benign filename parameter for ModSecurity and a different encoded filename* value that the backend prefers, causing MULTIPART_FILENAME rules and the application to make security decisions on different names. Applications that use the backend-selected name for storage, extension checks, or content-type inference can therefore receive a filename that bypassed WAF inspection. PHP's native multipart parser is not affected by this discrepancy. This issue is fixed in version 3.0.17.

Is CVE-2026-104269 actively exploited?

Active exploitation of CVE-2026-104269 has not been confirmed.

What is the CVSS score for CVE-2026-104269?

CVE-2026-104269 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:N/I:H/A:N.

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