CVE-2021-41103

Description

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.

How to fix CVE-2021-41103

To remediate CVE-2021-41103, upgrade the affected package to a fixed version below.

• —upgrade to 1.4.5~ds1-2+deb11u1 or later
• —upgrade to 1.4.5~ds1-2+deb11u1 or later
• —upgrade to 1.4.11 or later
• —upgrade to 1.4.11 or later

Is CVE-2021-41103 being exploited?

Low — EPSS is 0.3%, meaning exploitation activity has not been observed at scale.

Affected packages (4)

• from 0, < 1.4.5~ds1-2+deb11u1
• from 0, < 1.4.5~ds1-2+deb11u1
• from 0, < 1.4.11
• from 0, < 1.4.11, >= 1.5.0, < 1.5.7

CVSS scores

References (14)

• ADVISORYnvd.nist.gov/vuln/detail/CVE-2021-41103
• ADVISORYsecurity-tracker.debian.org/tracker/CVE-2021-41103
• PATCHgithub.com/containerd/containerd
• WEBcert-portal.siemens.com/productcert/pdf/ssa-222547.pdf