CVE-2026-30923
HIGHlibModSecurity3 denial of service via segfault when using t:hexDecode on single-character query strings
Title source: cnaDescription
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.
References (2)
Core 2
Core References
X_Refsource_Misc x_refsource_misc
https://github.com/owasp-modsecurity/ModSecurity/releases/tag/v3.0.15
X_Refsource_Confirm x_refsource_confirm
https://github.com/owasp-modsecurity/ModSecurity/security/advisories/GHSA-qrjc-3jpc-3h2g
Scores
CVSS v3
7.5
EPSS
0.0043
EPSS Percentile
34.5%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-125
Status
published
Products (2)
owasp/modsecurity
< 3.0.15
owasp-modsecurity/ModSecurity
< 3.0.15
Published
May 05, 2026
Tracked Since
May 06, 2026