First published: Tue Mar 22 2022(Updated: )
A bug was found in Moby (Docker Engine) where containers were incorrectly started with non-empty inheritable Linux process capabilities, creating an atypical Linux environment and enabling programs with inheritable file capabilities to elevate those capabilities to the permitted set during execve(2). Normally, when executable programs have specified permitted file capabilities, otherwise unprivileged users and processes can execute those programs and gain the specified file capabilities up to the bounding set. Due to this bug, containers which included executable programs with inheritable file capabilities allowed otherwise unprivileged users and processes to additionally gain these inheritable file capabilities up to the container's bounding set. Containers which use Linux users and groups to perform privilege separation inside the container are most directly impacted. This bug did not affect the container security sandbox as the inheritable set never contained more capabilities than were included in the container's bounding set. Patches This bug has been fixed in Moby (Docker Engine) 20.10.14. Users should update to this version as soon as possible. Running containers should be stopped, deleted, and recreated for the inheritable capabilities to be reset. This fix changes Moby (Docker Engine) behavior such that containers are started with a more typical Linux environment. Refer to capabilities(7) for a description of how capabilities work. Note that permitted file capabilities continue to allow for privileges to be raised up to the container's bounding set and that processes may add capabilities to their own inheritable set up to the container's bounding set per the rules described in the manual page. In all cases the container's bounding set provides an upper bound on the capabilities that can be assumed and provides for the container security sandbox. Workarounds The entrypoint of a container can be modified to use a utility like capsh(1) to drop inheritable capabilities prior to the primary process starting.
Credit: secalert@redhat.com
Affected Software | Affected Version | How to fix |
---|---|---|
Buildah Project Buildah | <1.25.0 | |
Fedoraproject Fedora | =34 | |
Fedoraproject Fedora | =35 | |
Fedoraproject Fedora | =36 | |
Redhat Enterprise Linux | =7.0 | |
Redhat Enterprise Linux | =8.0 | |
redhat/buildah | <1.25.0 | 1.25.0 |
The entry point of a container can be modified to use a utility like capsh(1) to drop inheritable capabilities prior to the primary process starting.
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(Appears in the following advisories)
CVE-2022-27651 is a vulnerability in buildah where containers were started with incorrect default permissions.
The severity of CVE-2022-27651 is medium with a CVSS score of 6.8.
The buildah package version up to and including 1.25.0, Buildah Project Buildah version up to and including 1.25.0, Fedora versions 34, 35, and 36, and Redhat Enterprise Linux versions 7.0 and 8.0 are affected by CVE-2022-27651.
To fix CVE-2022-27651, update to buildah version 1.25.0 or apply the relevant patches provided by Redhat for affected software versions.
You can find more information about CVE-2022-27651 in the following references: [Bugzilla Entry](https://bugzilla.redhat.com/show_bug.cgi?id=2070114), [Redhat Security Advisory](https://access.redhat.com/errata/RHSA-2022:1407), [Redhat Security Advisory](https://access.redhat.com/errata/RHSA-2022:1565).