CVE-2022-0492
Linux kernel cgroups v1 privilege-escalation flaw permitting container escape to root on the host.
Last refreshed: 7 June 2026 · Appears in 1 active topic
Can a four-year-old container bug still break out of Kubernetes today?
Timeline for CVE-2022-0492
Old Linux container bug back in the wild
Cybersecurity: Threats and Defences- What is CVE-2022-0492 and how does it escape from a container?
- CVE-2022-0492 exploits the Linux cgroups v1 release_agent mechanism. A process inside a container writes to the host's release_agent file, causing the kernel to execute arbitrary commands as host root when the container exits. The kernel does not check whether the writing process has host-level privileges, so any code running inside an unprotected container can break out.Source: Trail of Bits container security analysis, CISA KEV advisory
- Is my Kubernetes cluster protected against CVE-2022-0492?
- Kubernetes clusters with Pod Security Admission (PSA) enforced that restrict privileged container capabilities are substantially protected. Bare-metal Docker deployments without PSA or AppArmor/SELinux profiles remain fully exposed. You should also verify your kernel has applied the February 2022 patch and that Falco rulesets are updated to detect the anomalous cgroup_write syscall.Source: Trail of Bits, CNNVD assessment
- Why was a 2022 Linux container vulnerability only added to CISA's urgent list in 2026?
- CISA adds flaws to the Known Exploited Vulnerabilities catalogue only after confirming active exploitation in the wild. Vendors and distributions patched CVE-2022-0492 quickly in February 2022, but CISA's exploitation-confirmation threshold was not met until 2026, when threat actors began actively exploiting the flaw against unpatched targets.Source: CISA KEV policy documentation
Background
CVE-2022-0492 is a privilege-escalation and container-escape vulnerability in the Linux kernel's cgroups v1 subsystem. It exploits the release_agent mechanism: a process inside a container can write to the host's cgroup release_agent file and execute arbitrary commands at host-root level when the container exits. The kernel does not validate whether the writing process holds sufficient privilege relative to the host namespace, relying instead on the container runtime (Docker, containerd) and orchestrator (Kubernetes) to apply controls at a higher layer. When those controls are absent or misconfigured, the cgroups subsystem provides no independent defence. A kernel patch was shipped in February 2022 and major distributions including Red Hat, Ubuntu and Debian followed within a week. CISA added the flaw to the Known Exploited Vulnerabilities catalogue on 2 June 2026 with a 5 June federal deadline after confirming active exploitation in the wild.
Trail of Bits confirmed the flaw bypasses seccomp and AppArmor filters typically applied to containerised workloads when runtime Falco rulesets predate the February 2022 patch. Kubernetes environments with enforced Pod Security Admission (PSA) restrict the privileged container capabilities required for the release_agent write; bare-metal Docker deployments without PSA remain fully exposed. The four-year lag between patch and KEV listing reflects CISA's exploitation-confirmation threshold being met only in 2026, not slow vendor patching.
For cloud and Kubernetes operators, a container escape to host root collapses the isolation that all workloads on a shared node depend on. An attacker with code execution inside any container on the host can pivot to the host's file system, network interfaces, and other containers without a separate exploit. CISA's three-day deadline, compared to the 21 days granted to Oracle WebLogic in the same June batch, reflects the speed at which a container escape translates into wider infrastructure compromise.