CVE-2026-104269
ModSecurity: RFC 2231 `filename*` Parameter Bypasses Multipart Filename Rules on RFC-Compliant Backends (Go, Python, Node, Java)
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.
INFO
Published Date :
Nov. 5, 2026, 4:17 p.m.
Last Modified :
Nov. 5, 2026, 4:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update ModSecurity to version 3.0.17.
- Verify WAF and application use the same filename.
- Review Content-Disposition header handling.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-104269.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-104269 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-104269
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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The following list is the news that have been mention
CVE-2026-104269 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-104269 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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New CVE Received by [email protected]
Nov. 05, 2026
Action Type Old Value New Value Added 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. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N Added CWE CWE-436 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/104xxx/CVE-2026-104269.json">CVE-2026-104269</a> Added Reference https://github.com/owasp-modsecurity/ModSecurity/commit/463db0c840fa27bfba095b0406a63004a12884b0 Added Reference https://github.com/owasp-modsecurity/ModSecurity/commit/c6bd53d2dd96766b3afdc35d9929ebb20925d13d Added Reference https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v2.9.15 Added Reference https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.17 Added Reference https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-5pww-8rfg-9crf