CVE-2026-109088 is a security vulnerability in the X.Org X11 libXtst runtime library. Multiple issues were found in the X client library implementations, leading to the release of security fixes. The vulnerability affects versions of libXtst prior to 1.2.4-4.oe2403sp3. The CVSS 3.1 base score is 6.5, indicating a medium severity with an impact on availability but no confidentiality or integrity loss. A patch is available in version 1.2.4-4.oe2403sp3.