CVE-2026-50256
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk5th percentile - higher than 5% of all known CVEs
Summary
A stack-based buffer overflow vulnerability was found in the X.Org X server and Xwayland. A mismatch between the X server and the libXfont2 library's maximum font name length causes a stack buffer overflow during font alias resolution. The server allocates a 256-byte stack buffer but libXfont2's alias target name length is 1024 bytes.
Risk Assessment
An attacker could exploit this vulnerability to crash the X server or escalate privileges if the server runs as root. This could lead to system compromise or disruption of the graphical environment.
Recommendation
Immediately update the X.Org X server and Xwayland packages to a patched version. If an update is not possible, restrict access to the X server 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. A mismatch between the X server and the libXfont2 library's maximum font name length can cause a stack buffer overflow during font alias resolution. The server allocates a 256 byte stack buffer but libXfont2's alias target name length is 1024 bytes. A font alias name between 257 and 1023 bytes causes the X server to copy that name into the undersized stack buffer without further checks. This may be used to crash the server, or for privilege escalation if the X server runs as root.