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.
Published: 2026-07-10
Score: 8.6 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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History

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
References
Metrics cvssV3_1

{'score': 8.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N'}


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cve-icon 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

cve-icon Vulnrichment

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cve-icon NVD

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cve-icon Redhat

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cve-icon OpenCVE Enrichment

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Weaknesses
  • CWE-180

    Incorrect Behavior Order: Validate Before Canonicalize