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GHSA-rc4r-wh2q-q6c4
No affected components available
Moby is an open-source project created by Docker to enable software containerization. A bug was found in Moby (Docker Engine) where supplementary groups are not set up properly. If an attacker has direct access to a container and manipulates their supplementary group access, they may be able to use supplementary group access to bypass primary group restrictions in some cases, potentially gaining access to sensitive information or gaining the ability to execute code in that container. This bug is fixed in Moby (Docker Engine) 20.10.18. Users should update to this version when it is available. Running containers should be stopped and restarted for the permissions to be fixed. For users unable to upgrade, this problem can be worked around by not using the "USER $USERNAME" Dockerfile instruction. Instead by calling ENTRYPOINT ["su", "-", "user"] the supplementary groups will be set up properly.
Thanks to Steven Murdoch for reporting this issue.
Impact
If an attacker has direct access to a container and manipulates their supplementary group access, they may be able to use supplementary group access to bypass primary group restrictions in some cases, potentially gaining access to sensitive information or gaining the ability to execute code in that container.
Patches
This bug is fixed in Moby (Docker Engine) 20.10.18. Users should update to this version when it is available.
Workarounds
This problem can be worked around by not using the "USER $USERNAME" Dockerfile instruction. Instead by calling ENTRYPOINT ["su", "-", "user"] the supplementary groups will be set up properly.
References
https://www.benthamsgaze.org/2022/08/22/vulnerability-in-linux-containers-investigation-and-mitigation/
For more information
If you have any questions or comments about this advisory:
- Open an issue
- Email us at security@docker.com
The vulnerability requires local access to the device to be exploited. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data. There is a low impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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