VULNERABILITY INTELLIGENCE
CVE-2026-50257
CVSS score7.8 HIGH
EPSS probability0.14%
CISA KEVNot currently listed
Published2026-06-05
Last modified2026-08-05
CVSS vectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Description
A use-after-free flaw was found in the X.Org X server and Xwayland in miSyncDestroyFence(). A client that sets up multiple fence triggers can trigger a use-after-free function pointer call. An attacker would connect to the X server to set up a fence and await that fence, then a second X connection destroys the fence, causing the use-after-free. This may be used to crash the server, or for privilege escalation if the X server runs as root.
Weakness classification
- secalert@redhat.com: CWE-416
- 0b0ca135-0b70-47e7-9f44-1890c2a1c46c: CWE-416