How severe is CVE-2021-41089?

CVE-2021-41089 has a CVSS score of 6.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-41089?

CVE-2021-41089 affects the following packages: github.com/docker/docker (Go). Ecosystems affected: Go.

How do I fix CVE-2021-41089?

Update github.com/docker/docker to 20.10.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41089 is resolved across your whole dependency graph.

How do I detect CVE-2021-41089 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/docker/docker, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-41089 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2021-41089 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-41089 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-41089?

CVE-2021-41089 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 22th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-41089?

CVE-2021-41089 is classified as CWE-281 (CWE-281). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-41089 published, and has it been updated?

CVE-2021-41089 was published on October 4, 2021 and was last updated on October 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

MEDIUM severity

CVE-2021-41089 — docker

MEDIUMFix: moby/moby@bce32e5

CVE-2021-41089 is a medium-severity (CVSS 6.3) CWE-281 vulnerability in github.com/docker/docker. A fix is available for github.com/docker/docker — see the affected versions and patch details below.

`docker cp` allows unexpected chmod of host files in Moby Docker Engine

Also known asGHSA-v994-f8vw-g7j4GO-2024-2913

Published

Oct 4, 2021

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs22th percentile — riskier than 22% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐹github.com/docker/docker

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

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.

Patches

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.

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

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/docker/docker`	all versions	20.10.9`go get github.com/docker/docker@v20.10.9`

Affected Products

2 products · 3 configurations

fedorafedoraproject

2 versions

3435

Application

mobymobyproject

< 20.10.9

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/docker/docker, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/docker/docker to 20.10.9 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-41089 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

In OpenShift Container Platform (OCP), Migration Toolkit for Virtualization (MTV) and Red Hat Quay some components bundle github.com/moby/moby, but successful exploitation requires using a specially crafted container, therefore impact to these components is LOW.

Product	Fixed in	Advisory
Migration Toolkit for Virtualization 2.2	`migration-toolkit-virtualization/mtv-controller-rhel8:2.2.0-39`	RHEA-2021:5066

Frequently Asked Questions

## 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. ## Patches 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. ## Workarounds Ensure you only run trusted containers. ## C