Summary
Workarounds
Ensure you only run trusted containers.
Credits
The Moby project would like to thank Lei Wang and Ruizhi Xiao for responsibly disclosing this issue in accordance with the Moby security policy.
For more information
If you have any questions or comments about this advisory:
- Open an issue
- Email us at [email protected] if you think you’ve found a security bug
Impact
A bug was found in Moby (Docker Engine) where attempting to copy files using docker cp into a specially-crafted container can result in Unix file permission changes for existing files in the host’s filesystem, widening access to others. This bug does not directly allow files to be read, modified, or executed without an additional cooperating process.
CVE-2021-41089 has a CVSS score of 2.8 (Low). The vector is requires local access, low privileges required, and no user interaction. 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 (20.10.9); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
This bug has been fixed in Moby (Docker Engine) 20.10.9. Users should update to this version as soon as possible. Running containers do not need to be restarted.
Frequently Asked Questions
- What is CVE-2021-41089? CVE-2021-41089 is a low-severity security vulnerability in github.com/docker/docker (go), affecting versions < 20.10.9. It is fixed in 20.10.9.
- How severe is CVE-2021-41089? CVE-2021-41089 has a CVSS score of 2.8 (Low). 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.
- Which versions of github.com/docker/docker are affected by CVE-2021-41089? github.com/docker/docker (go) versions < 20.10.9 is affected.
- Is there a fix for CVE-2021-41089? Yes. CVE-2021-41089 is fixed in 20.10.9. Upgrade to this version or later.
- Is CVE-2021-41089 exploitable, and should I be worried? Whether CVE-2021-41089 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
- What actually determines whether CVE-2021-41089 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.
- How do I fix CVE-2021-41089? Upgrade
github.com/docker/dockerto 20.10.9 or later.