Vulnerability Details CVE-2026-50259
A stack-based buffer overflow flaw was found in the X.Org X server and Xwayland. _XkbSetMapChecks() declares a fixed-size stack buffer mapWidths[256] indexed by key type index. The helper function CheckKeyTypes() writes to this buffer at a client-controlled offset, allowing a stack buffer overflow. 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 1.8%
CVSS Severity
CVSS v3 Score 7.8
References
- https://access.redhat.com/security/cve/CVE-2026-50259
- https://bugzilla.redhat.com/show_bug.cgi?id=2485384
- https://gitlab.freedesktop.org/xorg/xserver/-/commit/867b59b33bee669cb412f1314e47c52eacf6e00b
- https://lists.x.org/archives/xorg-announce/2026-June/003702.html
- https://redhat.atlassian.net/browse/PSIRTSUPT-16950