SDDM: Privilege Escalation — GLSA 202402-02

A vulnerability has been discovered in SDDM which can lead to privilege escalation.

Affected packages

Background

SDDM is a modern display manager for X11 and Wayland sessions aiming to be fast, simple and beautiful. It uses modern technologies like QtQuick, which in turn gives the designer the ability to create smooth, animated user interfaces.

Description

A vulnerability has been discovered in SDDM. Please review the CVE identifier referenced below for details.

Impact

SDDM passes the -auth and -displayfd command line arguments when starting the Xserver. It then waits for the display number to be received from the Xserver via the `displayfd`, before the Xauthority file specified via the `-auth` parameter is actually written. This results in a race condition, creating a time window in which no valid Xauthority file is existing while the Xserver is already running. The X.Org server, when encountering a non-existing, empty or corrupt/incomplete Xauthority file, will grant any connecting client access to the Xorg display. A local unprivileged attacker can thus create an unauthorized connection to the Xserver and grab e.g. keyboard input events from other legitimate users accessing the Xserver.

Workaround

There is no known workaround at this time.

Resolution

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=x11-misc/sddm-0.18.1-r6"
 

References

• CVE-2020-28049

Release date
February 03, 2024

Latest revision
February 03, 2024: 1

Severity
normal

Exploitable
local

Bugzilla entries

• 753104