CVE-2026-30923: owasp-modsecurity modsecurity Out-of-bounds Read

Vulnerability summary

CVE-2026-30923 is a high (CVSS 8.2) Out-of-bounds Read vulnerability in owasp-modsecurity modsecurity. EPSS estimates a 0.52% chance of exploitation in the next 30 days, higher than 42.5% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 05-05-2026
   PublishedVulnerability first disclosed.
2. 05-05-2026
   Last modifiedVulnerability information updated.

Description

ModSecurity is an open source, cross platform web application firewall (WAF) engine for Apache, IIS and Nginx. Libmodsecurity is one component of the ModSecurity v3 project. A segmentation fault occurs when a rule using the t:hexDecode transformation inspects a query string parameter containing a single character. An attacker can exploit this to crash worker processes, causing a denial of service. Service resumes once the attack stops as worker processes recover from the segfault. All versions before 3.0.15 of libModSecurity3 are affected. This has been patched in version 3.0.15.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.