Docker: Race condition in docker cp allows bind mount redirection to host path

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.2 · CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:N/I:H/A:H

EPSS

• CVE-2026-42306: 0.10% estimated exploitation activity in the next 30 days; percentile 1.03 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary A race condition during docker cp mount setup allows a malicious container to redirect a bind mount target to an arbitrary host path, potentially overwriting host files or causing denial of service. Details When copying files into a container, the daemon sets up a temporary filesystem view by bind-mounting volumes into a private mount namespace. During this setup, the mount destination is created inside the container root and then a bind mount is attached using the container-relative path resolved to an absolute host path. Between mountpoint creation and the mount() syscall, a process running inside the container can replace the destination (or a parent path component) with a symlink pointing to an arbitrary location on the host. The mount() syscall follows the symlink, causing the volume to be bind-mounted onto an arbitrary host path instead of the intended container path. Impact A malicious container can redirect a volume bind mount to an arbitrary host path. The impact…

Published by the source

18 May 2026, 17:53 UTC

Last modified by the source

12 Jun 2026, 21:59 UTC

Source last checked

26 Oct 2026, 15:23 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-rg2x-37c3-w2rh

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# Patch Next advisory brief: CVE-2026-42306

Advisory: Docker: Race condition in docker cp allows bind mount redirection to host path
IDs: CVE-2026-42306, GHSA-rg2x-37c3-w2rh
Record: https://patchnext.com/advisories/cve-2026-42306 (revision 1, source checked 26 Oct 2026, 15:23 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/moby/moby/v2 2.0.0-beta.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/moby/moby/v2: affected < 2.0.0-beta.14; fixed in 2.0.0-beta.14
- Go github.com/docker/docker: affected <= 28.5.2
- Go github.com/moby/moby: affected <= 28.5.2

## Suggested inspection (read-only)
- Go github.com/moby/moby/v2: check the installed version with your package manager.
- Go github.com/docker/docker: check the installed version with your package manager.
- Go github.com/moby/moby: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/moby/moby/v2, github.com/docker/docker, github.com/moby/moby.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-rg2x-37c3-w2rh (GitHub-reviewed advisory GHSA-rg2x-37c3-w2rh lists affected ranges: Go github.com/docker/docker >=0 =0 =0 <=28.5.2)

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