Database/Container, Kubernetes & orchestration

CRI-O: newline in HOME injects arbitrary lines into /etc/passwd, bypassing the CVE-2022-4318 fix

CVE-2026-15809Container, Kubernetes & orchestrationcurated

Impact

The fix for CVE-2022-4318 was incomplete and can be bypassed. Anyone who can set environment variables on a container can put a newline into HOME, and CRI-O writes the result into /etc/passwd - adding attacker-chosen account lines, including a UID 0 entry. Red Hat scores it 7.8 with high impact on confidentiality, integrity and availability. On a GPU node this is the usual escape ladder: a tenant who can shape a pod spec turns a normal workload into root on the node, which means access to every other tenant's GPUs, /dev/nvidia*, the kubelet credentials and the node's service account. Affected products listed include OpenShift Container Platform 4 and 4.22 and Confidential Compute Attestation.

Who can reach it

A local, low-privileged actor who can set environment variables on a container - that is, any tenant who can submit a pod spec or otherwise influence the container's env. Authentication to the cluster API is needed, but no cluster-admin rights.

What to do

Update CRI-O to the version in RHSA-2026:57361 (or your distribution's equivalent carrying cri-o PRs 6450 and 6524). On OpenShift this lands as a MachineConfig rollout, so plan cordon-and-drain per node: the CRI-O restart tears down running containers, and GPU workloads have to be rescheduled or checkpointed first. Interim mitigation is admission control that rejects pod specs with newlines in environment variable values, particularly HOME.

References

https://nvd.nist.gov/vuln/detail/CVE-2026-15809 https://access.redhat.com/errata/RHSA-2026:57361 https://github.com/cri-o/cri-o/pull/6524 https://bugzilla.redhat.com/show_bug.cgi?id=2500846

This entry is curated: imported from vendor advisories with machine assistance, not yet individually verified. Confirm against your vendor's advisory before acting, and report anything wrong.