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Ubuntu Security Notice USN-6940-2
January 13, 2025

snapd vulnerabilities
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A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS
- Ubuntu 16.04 LTS

Summary:

Several security issues were fixed in snapd.

Software Description:
- snapd: Daemon and tooling that enable snap packages

Details:

USN-6940-1 fixed vulnerabilities in snapd. This update provides the
corresponding updates for Ubuntu 18.04 LTS and Ubuntu 16.04 LTS.

Original advisory details:

 Neil McPhail discovered that snapd did not properly restrict writes to
 the /home/jslarraz/bin path in the AppArmor profile for snaps using the home
 plug. An attacker who could convince a user to install a malicious snap
 could use this vulnerability to escape the snap sandbox. (CVE-2024-1724)

 Zeyad Gouda discovered that snapd failed to properly check the file type
 when extracting a snap. An attacker who could convince a user to install
 a malicious snap containing non-regular files could then cause snapd to
 block indefinitely while trying to read from such files and cause a
 denial of service. (CVE-2024-29068)

 Zeyad Gouda discovered that snapd failed to properly check the
 destination of symbolic links when extracting a snap. An attacker who
 could convince a user to install a malicious snap containing crafted
 symbolic links could then cause snapd to write out the contents of the
 symbolic link destination into a world-readable directory. This in-turn
 could allow a local unprivileged user to gain access to privileged
 information. (CVE-2024-29069)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 18.04 LTS
  snapd                           2.61.4ubuntu0.18.04.1+esm1
                                  Available with Ubuntu Pro

Ubuntu 16.04 LTS
  snapd                           2.61.4ubuntu0.16.04.1+esm1
                                  Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-6940-2
  https://ubuntu.com/security/notices/USN-6940-1
  CVE-2024-1724, CVE-2024-29068, CVE-2024-29069