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Vulnerability record · CVE-2026-52747 · published 10 July 2026

CVE-2026-52747: Owasp modsecurity vulnerability

Owasp · Modsecurity

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.

8.6 CVSS 3.1 High EPSS 0.48% · top 61.4% CWE-180 · CWE-180
8.6CVSS 3.1 base score
0.48%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 2 tagged exploit
14 Jul 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/owasp-modsecurity/ModSecurity/commit/875504c2758169c41be1ad2f0cc64d896b7815d7 Patch
https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.16 ProductRelease Notes
https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-rcw9-2f5r-7p88 ExploitMitigationVendor Advisory
https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-rcw9-2f5r-7p88 ExploitMitigationVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

8.6CVE-2024-1019Owasp modsecurity improper input validation vulnerabilityModSecurity / libModSecurity 3.0.0 to 3.0.11 is affected by a WAF bypass for path-based payloads submitted via specially crafted request URLs. ModSec…EPSS 0.69%8.2CVE-2026-42268Owasp modsecurity vulnerabilityModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 to before 3.0.15, there is …EPSS 0.49%8.2CVE-2026-30923Owasp modsecurity out-of-bounds read vulnerabilityModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Libmodsecurity is one component of the…EPSS 0.52%7.5CVE-2025-48866Owasp modsecurity vulnerabilityModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Versions prior to 2.9.10 contain a den…EPSS 0.83%7.5CVE-2023-38285Owasp modsecurity vulnerabilityTrustwave ModSecurity 3.x before 3.0.10 has Inefficient Algorithmic Complexity.EPSS 0.90%7.5CVE-2023-28882Owasp modsecurity uncontrolled resource consumption vulnerabilityTrustwave ModSecurity 3.0.5 through 3.0.8 before 3.0.9 allows a denial of service (worker crash and unresponsiveness) because some inputs cause a seg…EPSS 0.73%7.5CVE-2022-48279Owasp modsecurity interpretation conflict vulnerabilityIn ModSecurity before 2.9.6 and 3.x before 3.0.8, HTTP multipart requests were incorrectly parsed and could bypass the Web Application Firewall. NOTE…EPSS 1.2%7.5CVE-2021-42717Owasp modsecurity vulnerabilityModSecurity 3.x through 3.0.5 mishandles excessively nested JSON objects. Crafted JSON objects with nesting tens-of-thousands deep could result in th…EPSS 3.1%

Source: NIST National Vulnerability Database (record CVE-2026-52747), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.