owasp-modsecurity ModSecurity up to 3.0.15 Request Body Parser multipart.cc cross site scripting

Summaryinfo

A vulnerability labeled as problematic has been found in owasp-modsecurity ModSecurity up to 3.0.15. The affected element is an unknown function of the file src/request_body_processor/multipart.cc of the component Request Body Parser. Such manipulation leads to cross site scripting. This vulnerability is uniquely identified as CVE-2026-52747. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability was found in owasp-modsecurity ModSecurity up to 3.0.15. It has been rated as problematic. Affected by this issue is an unknown part of the file src/request_body_processor/multipart.cc of the component Request Body Parser. The manipulation with an unknown input leads to a cross site scripting vulnerability. Using CWE to declare the problem leads to CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Impacted is integrity. CVE summarizes:

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Prior to 3.0.16, the multipart/form-data request body parser in libmodsecurity silently removes embedded line breaks from non-file form-field values before exporting them to ARGS and ARGS_POST because src/request_body_processor/multipart.cc overwrites reserved bytes in m_reserve instead of appending the current buffer. This creates a parser differential between ModSecurity and backend applications that preserve line breaks in form fields, allowing rules that inspect ARGS or ARGS_POST to miss payloads whose dangerous syntax depends on a line break. This issue is fixed in version 3.0.16.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-52747 since 06/08/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project.

Upgrading to version 3.0.16 eliminates this vulnerability.

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Productinfo

Vendor

• owasp-modsecurity

Name

• ModSecurity

Version

• 3.0.0
• 3.0.1
• 3.0.2
• 3.0.3
• 3.0.4
• 3.0.5
• 3.0.6
• 3.0.7
• 3.0.8
• 3.0.9
• 3.0.10
• 3.0.11
• 3.0.12
• 3.0.13
• 3.0.14
• 3.0.15

Website

• Product: https://github.com/owasp-modsecurity/ModSecurity/

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