A flaw was found in the X.Org X server. This vulnerability, an out-of-bounds read, affects the XKB (X Keyboard Extension) modifier map handling. An attacker with access to the X11 server can exploit this by sending a malformed request, which causes the server to read beyond its intended memory boundaries. This can lead to the exposure of sensitive information or cause the server to crash, resulting in a denial of service.
To mitigate this vulnerability, restrict access to the X11 server. If the X.Org X server is not required on a system, consider disabling or uninstalling it. For systems where the X server is necessary, ensure that access is limited to trusted users and networks. This can involve configuring xhost or implementing firewall rules to restrict connections to the X server. Any changes to X server configuration or service status may require a restart of the X server for the mitigation to take effect, which will impact active graphical sessions.