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.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
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| owasp-modsecurity | ModSecurity | affected |
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Fri, 10 Jul 2026 22:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | 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. | |
| Title | ModSecurity: Multipart form-data parser silently strips embedded line breaks from form-field values, enabling request-body inspection bypass | |
| Weaknesses | CWE-180 | |
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| Metrics |
cvssV3_1
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MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-07-10T21:42:11.503Z
Reserved: 2026-06-08T14:00:43.573Z
Link: CVE-2026-52747
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