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.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2020-28049)

Note that Nessus relies on the presence of the package as reported by the vendor.

The remote host is affected by the vulnerability described in GLSA-202402-02 (SDDM: Privilege Escalation)

  - 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. (CVE-2020-28049)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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. (CVE-2020-28049)

The remote Fedora 33 host has a package installed that is affected by a vulnerability as referenced in the FEDORA-2021-7066b95c99 advisory.

  - 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. (CVE-2020-28049)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

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.

For Debian 9 'Stretch', this problem has been fixed in version 0.14.0-4+deb9u2.

We recommend that you upgrade your sddm packages.

For the detailed security status of sddm please refer to its security tracker page at: https://security-tracker.debian.org/tracker/sddm

NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

This update for sddm fixes the following issue :

  - Fix X not having access control on startup (boo#1177201,     CVE-2020-28049).

Fabian Vogt discovered a flaw in sddm, a modern display manager for X11. A local attacker can take advantage of a race condition when creating the Xauthority file to escalate privileges.

ID	Name	Product	Family	Severity
250078	Linux Distros Unpatched Vulnerability : CVE-2020-28049	Nessus	Misc.	medium
189971	GLSA-202402-02 : SDDM: Privilege Escalation	Nessus	Gentoo Local Security Checks	medium
407139	Alpine: multiple sddm packages: security update to 0.19.0-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	medium
407139	Alpine: multiple sddm packages: security update to 0.19.0-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	medium
145315	Fedora 33 : sddm (2021-7066b95c99)	Nessus	Fedora Local Security Checks	medium
142633	Debian DLA-2436-1 : sddm security update	Nessus	Debian Local Security Checks	medium
142627	openSUSE Security Update : sddm (openSUSE-2020-1870)	Nessus	SuSE Local Security Checks	medium
142513	Debian DSA-4783-1 : sddm - security update	Nessus	Debian Local Security Checks	medium

Detections

Analytics

CVE-2020-28049

medium

Tenable Plugins

medium

medium

medium

medium

medium

medium

medium

medium