Log in Start free

Vulnerability · Published Nov 5, 2026 · Assigned by GitHub_M

CVE-2026-104269ModSecurity: RFC 2231 `filename*` Parameter Bypasses Multipart Filename Rules on RFC-Compliant Backends (Go, Python, Node, Java)

High 8.6

In plain English

A high-severity security flaw in ModSecurity from owasp-modsecurity. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities).

Severity (CVSS 3.1)8.6High
Exploit odds (30 days)0.6%top 52.7% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official 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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12modsecurityno fix listedDEBIAN-CVE-2026-104269
Debian:13modsecurityno fix listedDEBIAN-CVE-2026-104269
Debian:14modsecurityno fix listedDEBIAN-CVE-2026-104269
Debian:12modsecurity-apacheno fix listedDEBIAN-CVE-2026-104269
Debian:13modsecurity-apacheno fix listedDEBIAN-CVE-2026-104269
Debian:14modsecurity-apacheno fix listedDEBIAN-CVE-2026-104269
Ubuntu:22.04:LTSmodsecurityno fix listedUBUNTU-CVE-2026-104269
Ubuntu:24.04:LTSmodsecurityno fix listedUBUNTU-CVE-2026-104269
Ubuntu:26.04:LTSmodsecurityno fix listedUBUNTU-CVE-2026-104269
Ubuntu:26.10modsecurityno fix listedUBUNTU-CVE-2026-104269
Ubuntu:26.04:LTSmodsecurity-apacheno fix listedUBUNTU-CVE-2026-104269
Ubuntu:26.10modsecurity-apacheno fix listedUBUNTU-CVE-2026-104269

Affected products (as reported)

VendorProductVersions
owasp-modsecurity ModSecurity >= 3.0.0, < 3.0.17

Weakness: CWE-436 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

References