Vulnerability Details CVE-2026-50261
A use-after-free flaw was found in the X.Org X server and Xwayland in SyncChangeCounter(). A client that sets up multiple SyncCounters can trigger a use-after-free when destroying those counters via a second client connection while changing those counters. This may be used to crash the server, or for privilege escalation if the X server runs as root.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 2.4%
CVSS Severity
CVSS v3 Score 7.8
References
- https://access.redhat.com/security/cve/CVE-2026-50261
- https://bugzilla.redhat.com/show_bug.cgi?id=2485386
- https://gitlab.freedesktop.org/xorg/xserver/-/commit/bdd7bf57af208b1ddf57d4683d67104443b44812
- https://lists.x.org/archives/xorg-announce/2026-June/003702.html
- https://redhat.atlassian.net/browse/PSIRTSUPT-16950