CVE-2021-41103

Insufficiently restricted permissions on plugin directories

Workarounds

Limit access to the host to trusted users. Update directory permission on container bundles directories.

For more information

If you have any questions or comments about this advisory:

• Open an issue in github.com/containerd/containerd
• Email us at [email protected]

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.

Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.

CVE-2021-41103 has a CVSS score of 5.9 (Medium). The vector is requires local access, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.4.11, 1.5.7); upgrading removes the vulnerable code path.

Kodem intelligence

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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.

1. What is CVE-2021-41103? CVE-2021-41103 is a medium-severity path traversal vulnerability in github.com/containerd/containerd (go), affecting versions < 1.4.11. It is fixed in 1.4.11, 1.5.7. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
2. How severe is CVE-2021-41103? CVE-2021-41103 has a CVSS score of 5.9 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/containerd/containerd are affected by CVE-2021-41103? github.com/containerd/containerd (go) versions < 1.4.11 is affected.
4. Is there a fix for CVE-2021-41103? Yes. CVE-2021-41103 is fixed in 1.4.11, 1.5.7. Upgrade to this version or later.
5. Is CVE-2021-41103 exploitable, and should I be worried? Whether CVE-2021-41103 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-41103 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-41103?
   • Upgrade github.com/containerd/containerd to 1.4.11 or later
   • Upgrade github.com/containerd/containerd to 1.5.7 or later

Other vulnerabilities in github.com/containerd/containerd