Vulnerabilities
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CVE Vulnerabilities

CVE-2021-32760

Incorrect Permission Assignment for Critical Resource

Published: Jul 19, 2021 | Modified: Jan 31, 2024
CVSS 3.x
6.3
MEDIUM
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
CVSS 2.x
6.8 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:P
RedHat/V2
RedHat/V3
Ubuntu
Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2021-32760
CWEhttps://cwe.mitre.org/data/definitions/732.html

containerd is a container runtime. A bug was found in containerd versions prior to 1.4.8 and 1.5.4 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. This bug has been fixed in containerd 1.5.4 and 1.4.8. As a workaround, ensure that users 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 specific files.

Weakness

The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.

Affected Software

Name Vendor Start Version End Version
Containerd Linuxfoundation * 1.4.8 (excluding)
Containerd Linuxfoundation 1.5.0 (including) 1.5.4 (excluding)

Potential Mitigations

  • Run the code in a “jail” or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
  • OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
  • This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
  • Be careful to avoid CWE-243 and other weaknesses related to jails.

References

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