Out-of-bounds read in ModSecurity - CVE-2026-30923
Published: April 29, 2026
Vulnerability identifier: #VU128453
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-30923
CWE-ID: CWE-125
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause a denial of service.
The vulnerability exists due to out-of-bounds read in the t:hexDecode transformation when processing query strings containing a single character under a rule that inspects query string arguments. A remote attacker can send a specially crafted request to cause a denial of service.
Only configurations that use the t:hexDecode transformation on query string inspection are vulnerable.
Affected software
ModSecurity
How to mitigate CVE-2026-30923
Install security update from vendor's website.
ModSecurity - addressed in versions 2.9.13, 3.0.15