GHSA-5pww-8rfg-9crf: ModSecurity: RFC 2231 `filename*` Parameter Bypasses Multipart Filename Rules on RFC-Compliant Backends (Go, Python, Node, Java)

Published Nov 5, 2026
·
Updated

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 MULTIPARTFILENAME 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.

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade ModSecurity to a version that resolves this vulnerability.

    Fixed in 3.0.17

Event History

Nov 5, 2026
CVE Published
via OSV·03:51 PM
Data Sourced
via OSV·03:51 PM
DescriptionSeverityWeakness

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