CVE-2026-52747: Owasp Modsecurity

High severity, CVSS 8.6. EPSS: 0.5% chance of exploitation in the next 30 days.

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.

Affected products

• Owasp Modsecurity: before 3.0.16 (fixed in 3.0.16)

Published 2026-07-10. Last modified 2026-07-14.