sddm: local privilege escalation due to race condition in creation of the Xauthority file (CVE-2020-28049)
An issue was discovered in SDDM before 0.19.0. It incorrectly starts the X server in a way that - for a short time period - allows local unprivileged users to create a connection to the X server without providing proper authentication. A local attacker can thus access X server display contents and, for example, intercept keystrokes or access the clipboard. This is caused by a race condition during Xauthority file creation.
References:
- https://nvd.nist.gov/vuln/detail/CVE-2020-28049
- https://www.openwall.com/lists/oss-security/2020/11/04/2
Affected branches:
-
master -
3.12-stable