Request-body inspection bypass via stripped line breaks
Published Jul 10, 2026 · Updated Jul 10, 2026
Request-body inspection bypass in OWASP ModSecurity before 3.0.16 allows remote attackers to evade WAF rules via multipart form fields. The multipart parser overwrites reserved CRLF or LF bytes when appending a non-file field chunk, so ARGS and ARGS_POST receive a collapsed value. Request-body inspection must be enabled and a rule must depend on the removed line break; the backend then receives dangerous syntax that the WAF did not inspect.
Summary
What happened
Request-body inspection bypass in OWASP ModSecurity before 3.0.16 allows remote attackers to evade WAF rules via multipart form fields. The multipart parser overwrites reserved CRLF or LF bytes when appending a non-file field chunk, so ARGS and ARGS_POST receive a collapsed value. Request-body inspection must be enabled and a rule must depend on the removed line break; the backend then receives dangerous syntax that the WAF did not inspect.
The record
- CVE
- CVE-2026-52747
- Published
- Jul 10, 2026
- Updated
- Jul 10, 2026
- Vendor
- OWASP ModSecurity
- Product
- ModSecurity
- Classifications
- CWE-180, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 10, 2026CVE publishedPublication date reported by the CVE source.
- Jul 10, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=< 3.0.16
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream multipart parser reproductionproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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