CVE-2026-50259
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk6th percentile - higher than 6% of all known CVEs
Summary
A stack-based buffer overflow vulnerability was found in the X.Org X server and Xwayland. The _XkbSetMapChecks() function declares a fixed-size stack buffer mapWidths[256] indexed by key type, and the helper CheckKeyTypes() writes to this buffer at a client-controlled offset, causing an overflow.
Risk Assessment
An attacker can crash the X server or, if the server runs as root, escalate privileges to gain full system control.
Recommendation
Immediately update X.Org X server and Xwayland packages to a patched version. If an update is not possible, restrict X server access to trusted users only.
Original NVD description (English source)
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.