What is CVE-2020-28049?

CVE-2020-28049 is a medium-severity vulnerability in Sddm Project, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 6.3/10. Published 2020-11-04.

How severe is CVE-2020-28049?

Medium severity. CVSS v3 base score is 6.3 out of 10.

Vulnerability in Sddm Project

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.

Vulnerability class: Race Condition

Published 2020-11-04 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.004 (33.4th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 33rd percentile — 33.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000

Affected products

Sddm Project
Debian Linux — versions 9.0, 10.0
Fedoraproject Fedora — versions 33
openSUSE Leap — versions 15.1, 15.2

Weakness classification (CWE)

CWE-362 — Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition)

References

github.com/sddm/sddm/releases (Third Party Advisory, Release Notes)
bugzilla.suse.com/show_bug.cgi (Exploit, Third Party Advisory, Issue Tracking)
github.com/sddm/sddm/blob/v0.19.0/ChangeLog (Third Party Advisory, Release Notes)
www.debian.org/security/2020/dsa-4783 (vendor-advisory, Third Party Advisory)
lists.debian.org/debian-lts-announce/2020/11/msg00009.html (mailing-list, Mailing List, Third Party Advisory)
lists.opensuse.org/opensuse-security-announce/2020-11/msg00031.html (vendor-advisory, Mailing List, Third Party Advisory)
lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
security.gentoo.org/glsa/202402-02 (vendor-advisory)

Frequently asked questions

What is CVE-2020-28049?: CVE-2020-28049 is a medium-severity vulnerability in Sddm Project, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 6.3/10. Published 2020-11-04.
How severe is CVE-2020-28049?: Medium severity. CVSS v3 base score is 6.3 out of 10.