Debian Security Advisory

DLA-2436-1 sddm -- LTS security update

Date Reported:
06 Nov 2020
Affected Packages:
Security database references:
In Mitre's CVE dictionary: CVE-2020-28049.
More information:

It was discovered that there was an issue in the sddm display manager where local unprivileged users could create a connection to the X server.

  • 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.

For Debian 9 Stretch, these problems have been fixed in version 0.14.0-4+deb9u2.

We recommend that you upgrade your sddm packages.

Further information about Debian LTS security advisories, how to apply these updates to your system and frequently asked questions can be found at: