CVE-2026-52761: modsecurity — Fix

Description

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 through 3.0.15, the t:utf8toUnicode transformation in src/actions/transformations/utf8_to_unicode.cc produces wrong output on i386 architecture because snprintf uses sizeof on a char pointer rather than the length of the unicode buffer, allowing rules that use this transformation to be bypassed on i386 architecture. This issue is fixed in version 3.0.16.

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CVSS v3.1 Score

5.8

MEDIUM

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

EPSS — Exploit Prediction

0.0041

Probability of exploitation

0.33%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-467 CWE-467

Affected Products

Vendor	Product	Versions
owasp	modsecurity	3.0.0 — 3.0.15

References

Advisories & Patches

https://github.com/owasp-modsecurity/ModSecurity/commit/edcd010814e234d46e2ec55a0f1078ff9d3032e4 https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-qjgm-7gp4-f8qq

Other References

https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.16

Frequently Asked Questions

What is CVE-2026-52761? +

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. From 3.0.0 through 3.0.15, the t:utf8toUnicode transformation in src/actions/transformations/utf8_to_unicode.cc produces wrong output on i386 architecture because snprintf uses sizeof on a char pointer rather than the length of the unicode buffer, allowing rules that use this transformation to be bypassed on i386 architecture. This issue is fixed in version 3.0.16. It has a CVSS v3.1 base score of 5.8 (MEDIUM).

How severe is CVE-2026-52761? +

CVE-2026-52761 has a CVSS v3.1 score of 5.8 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0041, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-52761? +

CVE-2026-52761 affects products from owasp, specifically: modsecurity. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-52761? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2026-52761