CVE-2021-21285

moby docker daemon crash during image pull of malicious image

Credits

Maintainers would like to thank Josh Larsen, Ian Coldwater, Duffie Cooley, Rory McCune for working on the vulnerability and Brad Geesaman for responsibly disclosing it to [email protected].

Pulling an intentionally malformed Docker image manifest crashes the dockerd daemon.

Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.

CVE-2021-21285 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (19.3.15, 20.10.3); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

Versions 20.10.3 and 19.03.15 contain patches that prevent the daemon from crashing.

1. What is CVE-2021-21285? CVE-2021-21285 is a medium-severity uncontrolled resource consumption vulnerability in github.com/moby/moby (go), affecting versions < 19.3.15. It is fixed in 19.3.15, 20.10.3. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
2. How severe is CVE-2021-21285? CVE-2021-21285 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of github.com/moby/moby are affected by CVE-2021-21285? github.com/moby/moby (go) versions < 19.3.15 is affected.
4. Is there a fix for CVE-2021-21285? Yes. CVE-2021-21285 is fixed in 19.3.15, 20.10.3. Upgrade to this version or later.
5. Is CVE-2021-21285 exploitable, and should I be worried? Whether CVE-2021-21285 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2021-21285 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2021-21285?
   • Upgrade github.com/moby/moby to 19.3.15 or later
   • Upgrade github.com/moby/moby to 20.10.3 or later

Other vulnerabilities in github.com/moby/moby