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[oss-security] CVE-2021-32760: containerd archive package allows chmod of file outside of unpack target directory



A bug was found in containerd where pulling and extracting a specially-
crafted container image can result in Unix file permission changes for
existing files in the host’s filesystem. Changes to file permissions
can deny access to the expected owner of the file, widen access to
others, or set extended bits like setuid, setgid, and sticky. This bug
does not directly allow files to be read, modified, or executed without
an additional cooperating process.

Patches
This bug has been fixed in containerd 1.5.4 and 1.4.8. Users should
update to these versions as soon as they are released. Running
containers do not need to be restarted.

Workarounds
Ensure you only pull images from trusted sources.

Linux security modules (LSMs) like SELinux and AppArmor can limit the
files potentially affected by this bug through policies and profiles
that prevent containerd from interacting with unexpected files.
For more information

If you have any questions or comments about this advisory:

Open an issue [1]
Email us at security AT containerd.io if you think you’ve found a security
bug.

View this advisory on the web: 
https://github.com/containerd/containerd/security/advisories/GHSA-c72p-9xmj-rx3w

On behalf of the containerd project,
Samuel Karp

[1] https://github.com/containerd/containerd/issues/new/choose