CVE-2026-52747
HIGHDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:N
Exploit Intelligence
Moderate risk: more likely to be exploited than 41% of all known CVEs.
References
Related Vulnerabilities
Other CWE-180 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-26136 | Critical | 9.8 | 5.0% | - | Fix |
| CVE-2022-26137 | High | 8.8 | 2.2% | - | Fix |
| CVE-2026-39364 | High | 7.5 | 2.1% | - | Fix |
| CVE-2025-43716 | Medium | 5.8 | 1.2% | - | - |
| CVE-2026-24895 | Critical | 9.8 | 0.6% | - | Fix |
| CVE-2026-27590 | Critical | 9.8 | 0.5% | - | Fix |
Common questions
How do I fix CVE-2026-52747?
Upgrade modsecurity on debian unstable to 3.0.16-1 or later.
Is CVE-2026-52747 being actively exploited?
Not that we know of. CVE-2026-52747 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.52% is the estimated probability that it will be exploited in the next 30 days. That is higher than 41% of all scored CVEs.
How severe is CVE-2026-52747?
CVE-2026-52747 has a CVSS v3 base score of 8.6, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-52747 affect?
Published advisories record a fix for modsecurity (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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Markdown
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-14.