What’s Vulnerable › Vulnerabilities

CVE-2020-28049

• Severity: medium (CVSS 6.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2020-11-04 · updated 2026-06-17
• Weakness: CWE-362

Description

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.

Affected products

• Debian Linux: 9.0, 10.0
• Fedoraproject Fedora: 33
• openSUSE Leap: 15.1, 15.2
• Sddm Project Sddm: before 0.19.0 — fixed in 0.19.0

How to fix

Upgrade to a fixed version: Sddm Project Sddm 0.19.0. Check the vendor advisory for mitigations.

References

• http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00031.html
• https://bugzilla.suse.com/show_bug.cgi?id=CVE-2020-28049
• https://github.com/sddm/sddm/blob/v0.19.0/ChangeLog
• https://github.com/sddm/sddm/releases
• https://lists.debian.org/debian-lts-announce/2020/11/msg00009.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GT3EX5NSQJJAKY63ENSMEDX6NYZLYY3S/
• https://security.gentoo.org/glsa/202402-02
• https://www.debian.org/security/2020/dsa-4783
• http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00031.html
• https://bugzilla.suse.com/show_bug.cgi?id=CVE-2020-28049
• https://github.com/sddm/sddm/blob/v0.19.0/ChangeLog
• https://github.com/sddm/sddm/releases

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