Vulnerability in Owasp Modsecurity
CVE-2026-52747
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 · last modified .
CVSS v3 metric
CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.005 (39.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Owasp Modsecurity
- Owasp-Modsecurity Modsecurity — versions < 3.0.16
Weakness classification (CWE)
References
- github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-rcw9-2f5r-7p88 (Exploit, Mitigation, Vendor Advisory)
- github.com/owasp-modsecurity/ModSecurity/commit/875504c2758169c41be1ad2f0cc64d8… (Patch)
- github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.16 (Product, Release Notes)
Frequently asked questions
- What is CVE-2026-52747?
- CVE-2026-52747 is a high-severity vulnerability in Owasp Modsecurity, classified under CWE-180. CVSS score: 8.6/10. Published 2026-07-10.
- How severe is CVE-2026-52747?
- High severity. CVSS v3 base score is 8.6 out of 10.