CVE-2026-42306 — docker
HIGHCVE-2026-42306 is a high-severity (CVSS 7.2) CWE-61 vulnerability in github.com/docker/docker. A fix is available for github.com/docker/docker — see the affected versions and patch details below.
Moby: Race condition in docker cp allows bind mount redirection to host path
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-42306.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-42306 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/docker/docker🐹github.com/moby/moby/v2🐹github.com/moby/mobyReal-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
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 depends on the volume content and mount options:
- If the volume is writable, arbitrary host files at the redirected path could be overwritten with the volume's contents.
- If the volume is read-only, the host path is masked by the mount for the duration of the operation, causing denial of service.
- In all cases the mount is temporary (torn down after the
docker cpcompletes), but the effects of any writes persist.
Conditions for exploitation
- A container must have at least one volume mount.
- A process inside the container must be able to rapidly create and swap symlinks at the volume mount destination path.
- An operator must initiate a
docker cpinto that container, or call thePUT /containers/{id}/archiveorHEAD /containers/{id}/archiveAPI endpoints.
Not affected
- Containers that do not have volume mounts are not affected, as the race occurs during volume bind-mount setup.
Workarounds
- Only run containers from trusted images.
- Avoid using
docker cpwith untrusted running containers. - Use authorization plugins to restrict access to the archive API endpoints (
PUT /containers/{id}/archive,HEAD /containers/{id}/archive).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/docker/docker | all versions | No fix |
| 🐹Go | github.com/moby/moby/v2 | all versions | 2.0.0-beta.14go get github.com/moby/moby/v2@v2.0.0-beta.14 |
| 🐹Go | github.com/moby/moby | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
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
No patched version of github.com/docker/docker has shipped for CVE-2026-42306 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-42306 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-42306. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
This is an Important flaw in the Moby container framework where a race condition during `docker cp` mount setup could allow a malicious container to overwrite arbitrary host files. Exploitation requires an attacker to have control over a running container, which could lead to data corruption or denial of service on…
| Product | Fixed in | Advisory |
|---|---|---|
| RHEM 1.1 for RHEL 10 | flightctl-0:1.1.4-1.el10em | RHSA-2026:68334 |
| Multicluster Global Hub 1.4.9 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1786621960 | RHSA-2026:55810 |
| Multicluster Global Hub 1.6.5 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1785863006 | RHSA-2026:54392 |
| Multicluster Global Hub 1.7.3 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1785442872 | RHSA-2026:53530 |
| OpenShift API for Data Protection 1.3 | oadp/oadp-mustgather-rhel9:1785177359 | RHSA-2026:51033 |
| OpenShift API for Data Protection 1.4 | oadp/oadp-mustgather-rhel9:1786946294 | RHSA-2026:59467 |
| OpenShift Developer Tools and Services 1.6.4 | source-to-image/source-to-image-rhel8:1784727697 | RHSA-2026:51057 |
| Red Hat Edge Manager 1.1 | rhem/flightctl-alert-exporter-rhel10:1789485396 | RHSA-2026:68044 |
Frequently Asked Questions
Is CVE-2026-42306 in your dependencies?
O3 Security finds CVE-2026-42306 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.