What is CVE-2024-21626?

A file descriptor leak in runc allows attackers to escape container isolation and gain root access to the host system. Affects Docker, Kubernetes, and other runc-based container runtimes.

How do I fix CVE-2024-21626?

Update runc to 1.1.12 or later. Update Docker to 25.0.2+ / 24.0.9+ and containerd to 1.7.13+ / 1.6.27+. Run containers as non-root with --user and --cap-drop=ALL. Enable Seccomp and AppArmor/SELinux profiles for containers. Restrict /proc access with read-only mounts where possible. Run containers in rootless mode (Podman, rootless Docker) for defense-in-depth.

Which versions are affected by CVE-2024-21626?

Affected: runc < 1.1.12. Fixed in: runc 1.1.12+.

highCVSS 8.6/10·Published: 2024-01-31·runc (Docker, Kubernetes, containerd)

How to fix CVE-2024-21626 – Step-by-Step Guide

CVE-2024-21626, dubbed "Leaky Vessels," is a high-severity runc vulnerability (CVSS 8.6) published on January 31, 2024. This critical flaw enables container escape, posing a significant risk to Docker, Kubernetes, and other runc-based environments.

CVE ID

CVE-2024-21626

Severity

HIGH

CVSS Score

8.6/10

Affected

runc (Docker, Kubernetes, containerd)

What is runc Container Escape – Leaky Vessels?

CVE-2024-21626 is a runc file descriptor leak affecting versions prior to 1.1.12. An attacker inside a container can exploit this leak via /proc/self/fd to break container isolation. This allows them to execute arbitrary code outside the container's sandbox.

Affected Versions

runc < 1.1.12

Fixed In

runc 1.1.12+

Official References

Impact and Risks for your Infrastructure

Successful exploitation of CVE-2024-21626 leads to a full container escape, granting root privileges on the host system. This can result in complete compromise of the underlying infrastructure, potential data breaches, and disruption of critical services.

runcdockerkubernetescontainer-escapehigh2024

Step-by-Step Mitigation Guide

To mitigate CVE-2024-21626, update runc to version 1.1.12 or higher immediately. Verify the update by checking your runc version. Ensure all affected container runtimes like Docker and Kubernetes are restarted to apply the patched runc binary effectively.

1Update runc to 1.1.12 or later.
2Update Docker to 25.0.2+ / 24.0.9+ and containerd to 1.7.13+ / 1.6.27+.
3Run containers as non-root with --user and --cap-drop=ALL.
4Enable Seccomp and AppArmor/SELinux profiles for containers.
5Restrict /proc access with read-only mounts where possible.
6Run containers in rootless mode (Podman, rootless Docker) for defense-in-depth.

Frequently Asked Questions

What is the CVSS score for CVE-2024-21626?▼

CVE-2024-21626 has a CVSS score of 8.6/10 (high severity). This reflects a significant security risk that should be addressed promptly.

Which versions of runc (Docker, Kubernetes, containerd) are affected?▼

Affected: runc < 1.1.12. The vulnerability was fixed in: runc 1.1.12+.

How long does it take to fix CVE-2024-21626?▼

For most teams: 15–60 minutes to apply the patch, plus 15 minutes of post-patch verification. Complex multi-service environments may require 2–4 hours including staging validation.

Is CVE-2024-21626 being actively exploited?▼

Check the NVD entry and CISA KEV catalog for exploitation status. As a high-severity vulnerability, treat it as a priority remediation regardless of known exploitation status.

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This CVE fix guide is based on publicly available security advisories (NVD, vendor bulletins). Always test changes in a staging environment before applying to production. Verify against the official vendor advisory for the most up-to-date guidance.