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CVE-2021-41103

Published: 4 October 2021

containerd is an open source container runtime with an emphasis on simplicity, robustness and portability. A bug was found in containerd where container root directories and some plugins had insufficiently restricted permissions, allowing otherwise unprivileged Linux users to traverse directory contents and execute programs. When containers included executable programs with extended permission bits (such as setuid), unprivileged Linux users could discover and execute those programs. When the UID of an unprivileged Linux user on the host collided with the file owner or group inside a container, the unprivileged Linux user on the host could discover, read, and modify those files. This vulnerability has been fixed in containerd 1.4.11 and containerd 1.5.7. Users should update to these version when they are released and may restart containers or update directory permissions to mitigate the vulnerability. Users unable to update should limit access to the host to trusted users. Update directory permission on container bundles directories.

Priority

High

Cvss 3 Severity Score

7.8

Score breakdown

Status

Package Release Status
containerd
Launchpad, Ubuntu, Debian
impish
Released (1.5.5-0ubuntu3)
trusty Does not exist

upstream
Released (1.4.11,1.5.7)
bionic
Released (1.5.2-0ubuntu1~18.04.3)
focal
Released (1.5.2-0ubuntu1~20.04.3)
hirsute
Released (1.5.2-0ubuntu1~21.04.3)
xenial
Released (1.2.6-0ubuntu1~16.04.6+esm2)
Available with Ubuntu Pro
jammy
Released (1.5.5-0ubuntu3)

Severity score breakdown

Parameter Value
Base score 7.8
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H