SB2022022426 - Ubuntu update for snapd

Description

This security bulletin contains information about 4 secuirty vulnerabilities.

1) Incorrect default permissions (CVE-ID: CVE-2021-3155)

The vulnerability allows a local user to gain access to sensitive information.

The vulnerability exists due to snapd creates "~/snap" directories in user home directories without specifying owner-only permissions. A local user can gain access to potentially sensitive information.

2) Input validation error (CVE-ID: CVE-2021-4120)

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to insufficient validation of snap content interface and layout paths. A local user can inject arbitrary AppArmor policy rules via malformed content interface and layout declarations and execute arbitrary code with elevated privileges.

3) UNIX hardlink following (CVE-ID: CVE-2021-44730)

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a hardlink following issue within the the snap-confine binary. A local user can create a hardlink to system binaries and execute them with elevated privileges.

4) Race condition (CVE-ID: CVE-2021-44731)

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a race condition in the snap-confine binary when preparing a private mount namespace for a snap.. A local user can  bind-mount their own contents inside the snap's private mount namespace and execute arbitrary code with root privileges.

Remediation

Install update from vendor's website.

References

• https://ubuntu.com/security/notices/USN-5292-4