What’s Vulnerable › Vulnerabilities

CVE-2021-41089: `docker cp` allows unexpected chmod of host files

• Severity: medium (CVSS 6.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-10-04 · updated 2026-06-17
• Weakness: CWE-281

Description

Moby is an open-source project created by Docker to enable software containerization. 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. 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.

Affected products

• Fedoraproject Fedora: 34, 35
• Docker Engine: before 20.10.9 — fixed in 20.10.9

How to fix

Upgrade to a fixed version: Docker Engine 20.10.9. Check the vendor advisory for mitigations.

References

• https://cert-portal.siemens.com/productcert/pdf/ssa-222547.pdf
• https://github.com/moby/moby/commit/bce32e5c93be4caf1a592582155b9cb837fc129a
• https://github.com/moby/moby/security/advisories/GHSA-v994-f8vw-g7j4
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/B5Q6G6I4W5COQE25QMC7FJY3I3PAYFBB/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNFADTCHHYWVM6W4NJ6CB4FNFM2VMBIB/
• https://cert-portal.siemens.com/productcert/pdf/ssa-222547.pdf
• https://github.com/moby/moby/commit/bce32e5c93be4caf1a592582155b9cb837fc129a
• https://github.com/moby/moby/security/advisories/GHSA-v994-f8vw-g7j4
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/B5Q6G6I4W5COQE25QMC7FJY3I3PAYFBB/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZNFADTCHHYWVM6W4NJ6CB4FNFM2VMBIB/

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