CVE-2026-52747 Details
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.
A vulnerability exists in the ModSecurity WAF engine's multipart/form-data request body parser, prior to version 3.0.16. The parser incorrectly removes embedded line breaks from non-file form-field values before sending them to ARGS and ARGS_POST. This issue creates a discrepancy between how ModSecurity and backend applications handle line breaks in form fields, potentially allowing certain payloads to bypass security rules. The vulnerability arises because the parser overwrites reserved bytes instead of appending them, leading to the loss of critical line break information.
Users can update to ModSecurity version 3.0.16 or later, where this issue has been fixed. Additionally, it is recommended to add regression tests for multipart form fields with embedded line breaks to ensure the parser handles these cases correctly.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jul 13, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-rcw9-2f5r-7p88 | CISA-ADP | ExploitMitigationVendor Advisory |
| https://github.com/owasp-modsecurity/ModSecurity/commit/875504c2758169c41be1ad2f0cc64d896b7815d7 | [email protected] | Patch |
| https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.16 | [email protected] | ProductRelease Notes |
| https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-rcw9-2f5r-7p88 | [email protected] | ExploitMitigationVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-180 | Incorrect Behavior Order: Validate Before Canonicalize | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| owasp modsecurity | < 3.0.16 |
CPE
Remediation
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Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 14, 2026 | Initial Analysis | [email protected] |
| Jul 13, 2026 | CVE Modified | CISA-ADP |
| Jul 10, 2026 | New CVE Received | [email protected] |