The fix for CVE-2022-4318 in CRI-O is incorrect and has been bypassable since it was introduced on December 14, 2022. The check in server/containercreate.go uses a Go raw string literal (\n) instead of an interpreted string literal ("\n"), causing it to search for the literal two-character sequence backslash-n (0x5c 0x6e) rather than an actual newline character (0x0a).
An attacker who can set environment variables on a container (via the CRI CreateContainer request) can supply a real newline character in the HOME environment variable, bypassing the check entirely. The unsanitized value is then passed to utils.GeneratePasswd, which uses fmt.Sprintf to construct the container's /etc/passwd content, allowing arbitrary line injection.
A flaw was discovered in CRI-O's checkpoint and restore capability. If a container is restored from a checkpoint archive, CRI-O does not adequately validate the restore metadata. A sufficiently privileged user could therefore cause unintended host filesystem activity during the restore process. This behavior is only reachable when checkpoint and restore has been explicitly enabled; it is not active in the default CRI-O/OpenShift configuration. Exploitation also depends on the attacker being able to initiate a restore operation using checkpoint data that they control or supply.
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.
An incorrect sysctls validation vulnerability was found in CRI-O 1.18 and earlier. The sysctls from the list of "safe" sysctls specified for the cluster will be applied to the host if an attacker is able to create a pod with a hostIPC and hostNetwork kernel namespace.
A flaw was found in cri-o, as a result of all pod-related processes being placed in the same memory cgroup. This can result in container management (conmon) processes being killed if a workload process triggers an out-of-memory (OOM) condition for the cgroup. An attacker could abuse this flaw to get host network access on an cri-o host.
Kubernetes CRI-O version prior to 1.9 contains a Privilege Context Switching Error (CWE-270) vulnerability in the handling of ambient capabilities that can result in containers running with elevated privileges, allowing users abilities they should not have. This attack appears to be exploitable via container execution. This vulnerability appears to have been fixed in 1.9.