CVE-2026-47262: 
Packer vulnerability analysis and mitigation

CVE-2026-47262 is a Denial of Service (DoS) vulnerability in containerd, the open-source container runtime, caused by unbounded group parsing when processing a maliciously crafted container image. When a container is created from such an image, memory exhaustion occurs, triggering an Out Of Memory (OOM) kill of the containerd process and rendering the container runtime API unavailable. Affected versions include 1.7.0–1.7.32, 2.0.0–2.0.9, 2.1.0–2.1.8, 2.2.0–2.2.4, and 2.3.0–2.3.1. The vulnerability was published on July 1, 2026, and carries a CVSS v3.1 base score of 5.5 (Medium) (GitHub Advisory, Red Hat CVE).

The root cause is uncontrolled resource consumption (CWE-400 / CWE-770) during the parsing of group metadata embedded in a container image. When containerd processes the image to create a container, it performs unbounded group parsing without enforcing memory limits or throttling, allowing an attacker-controlled image to drive memory usage to exhaustion. The attack vector is local (the image must be pulled or imported), requires user interaction (a user or orchestrator must initiate container creation), and no privileges are required to supply the malicious image. The vulnerability was independently discovered and responsibly disclosed by Jakub Ciolek (@jake-ciolek) at AlphaSense and Kyle Elliott at Trail of Bits (GitHub Advisory).

Successful exploitation causes the containerd process to be OOM-killed by the operating system, making the container runtime API completely unavailable. This disrupts dependent clients including Docker Engine and Kubernetes control-plane components (e.g., kubelet), potentially taking down entire node workloads or cluster management functions. There is no confidentiality or integrity impact; the vulnerability is limited to availability (GitHub Advisory, Red Hat Bugzilla).

1. Craft a malicious image: Create a container image with specially crafted group metadata (e.g., in /etc/group or equivalent image layer content) designed to trigger unbounded parsing loops or exponential memory allocation when processed by containerd's group parser.
2. Distribute the image: Push the malicious image to a registry accessible to the target environment, or supply it via a direct image import mechanism (e.g., ctr images import or docker pull from an attacker-controlled registry).
3. Trigger container creation: Induce a user, CI/CD pipeline, or Kubernetes scheduler to create a container from the malicious image. This can be achieved by social engineering, supply chain compromise, or by having write access to a shared registry.
4. Cause OOM kill: When containerd processes the image during container creation, memory is exhausted without bounds, causing the OS to OOM-kill the containerd process and rendering the container runtime API unavailable (GitHub Advisory).

• Logs: System logs (/var/log/syslog, journalctl -u containerd) showing OOM killer messages targeting the containerd process (e.g., Out of memory: Kill process <pid> (containerd)); containerd service crash/restart events.
• Process: Sudden termination of the containerd process followed by automatic restart; abnormal memory growth in the containerd process observable via top or ps before the OOM kill.
• Network/Registry: Unexpected pulls of unfamiliar or externally hosted container images immediately preceding the containerd crash; image pull events from untrusted or newly registered registries in container runtime audit logs.
• File System: Presence of unusual or recently added container image layers in the containerd image store (e.g., /var/lib/containerd/) with anomalous group-related metadata files.

Upgrade containerd to one of the patched versions: 1.7.33, 2.0.10, 2.1.9, 2.2.5, or 2.3.2 (GitHub Advisory). As a workaround where immediate patching is not possible, restrict container image sources to trusted registries and limit who can push images or schedule pods, preventing untrusted images from reaching the runtime. Implement image scanning and admission control policies (e.g., OPA Gatekeeper, Kyverno) to validate images before deployment (Red Hat CVE). AWS Amazon Linux and Ubuntu have also released updated packages addressing this CVE (AWS ALAS).

AWS published a security bulletin (2026-046) and blog post covering this vulnerability as part of their June 2026 security roundup, and released updated Amazon Linux packages (AWS Security Bulletin). Red Hat tracked the issue via Bugzilla with a broad CC list of 98 product security engineers, indicating wide internal triage across affected product lines (Red Hat Bugzilla). Google Cloud and Ubuntu also issued advisories and updated packages. Community discussion on Reddit's r/linuxadmin noted the moderate severity and straightforward remediation path. The oss-security mailing list carried a disclosure post, and the vulnerability was picked up by Linux security news aggregators including linuxsecurity.com and pro-linux.de.