Race condition in sddm - CVE-2020-28049
Published: November 4, 2020 / Updated: November 14, 2020
Vulnerability identifier: #VU48419
CSH Severity: Low
CVSS v4: 7.2 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2020-28049
CWE-ID: CWE-362
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local authenticated user to read and manipulate data.
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 software
sddm
Arch Linux
Gentoo Linux
Opensuse
Fedora
sddm (Alpine package)
sddm (Debian package)
x11-misc/sddm
sddm
Arch Linux
Gentoo Linux
Opensuse
Fedora
sddm (Alpine package)
sddm (Debian package)
x11-misc/sddm
sddm
How to mitigate CVE-2020-28049
Install update from vendor's website.
sddm - update to 0.19.0
sddm (Alpine package) - update to 0.19.0-r0
sddm (Debian package) - update to 0.18.0-1+deb10u1
x11-misc/sddm - update to 0.18.1-r6
sddm - update to 0.19.0-3.fc33
sddm (Alpine package) - update to 0.19.0-r0
sddm (Debian package) - update to 0.18.0-1+deb10u1
x11-misc/sddm - update to 0.18.1-r6
sddm - update to 0.19.0-3.fc33
External 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://www.debian.org/security/2020/dsa-4783