high CVSS 7.2 EPSS <0.1%

CVE-2026-42306·Docker vulnerability

Moby is an open source container framework. In Docker Engine prior to version 29.5.1, Docker Daemon versions 28.5.2 and prior, and Moby Daemon prior to version 2.0.0-beta.14, 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. This issue has been patched in Docker Engine version 29.5.1 and Moby Daemon version 2.0.0-beta.14.

Severity
high
Software
Docker
Fixed in
29.5.1
Published

How likely is exploitation

FIRST's Exploit Prediction Scoring System puts the probability of this CVE being exploited in the next 30 days at <0.1% — higher than 2% of all published CVEs. EPSS is an independent forecast of exploitation, not a severity rating: it says nothing about how much damage a successful attack does, which is what a CVSS score measures.

Read the two together. CVE-2026-42306 scores 7.2 on CVSS, so a successful attack would be serious — but at <0.1%, almost nobody is currently attempting it. That is a different situation from a flaw under mass exploitation, and it is usually the difference between patching on your next maintenance window and patching tonight.

Affected versions

Until: 28.5.2

Fixed in: 29.5.1

How to fix this CVE

Update Docker Engine to version 29.5.1 or later to address a race condition in the docker cp mount setup process. This vulnerability allows containers to redirect bind mounts to arbitrary host paths, risking file overwrites or service disruption. Prioritize this update for systems running Docker 28.5.2 or earlier where containers have elevated privileges or untrusted workloads are present.

sudo dnf update docker-ce --assumeyes

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'docker version --format {{.Server.Version}}' to retrieve the currently installed Docker daemon version and compare against 28.5.2 or earlier
  2. Check if containers with volume mount capabilities are running via 'docker ps --format "table {{.Names}}\t{{.Mounts}}"' to identify which workloads use bind mounts
  3. Search Docker daemon logs for mount-related errors using 'sudo journalctl -u docker -g "mount" --since "24 hours ago"' to detect failed or suspicious mount operations
  4. Verify the patched version was applied by running 'docker version' again and confirming the Server version is 29.5.1 or higher

FAQ

What is CVE-2026-42306?

This vulnerability is a race condition in Docker's cp command mount setup that permits a malicious container to redirect bind mount targets to unintended host paths, potentially leading to unauthorized file modification or denial of service attacks.

Is CVE-2026-42306 being actively exploited?

No, there is no evidence of active exploitation in the wild according to CISA's Known Exploited Vulnerabilities catalog, and no public exploits are currently available.

What versions of Docker are affected by CVE-2026-42306?

Docker Engine versions prior to 29.5.1, Docker Daemon versions 28.5.2 and earlier, and Moby Daemon versions prior to 2.0.0-beta.14 are vulnerable.

How do I check if my server is vulnerable to CVE-2026-42306?

Execute 'docker --version' or 'docker version --format {{.Server.Version}}' and verify the version is 29.5.1 or later; if it shows 28.5.2 or earlier, your system requires patching.

Does Defensia detect CVE-2026-42306?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Docker is installed on a monitored server, CVE-2026-42306 will appear in your dashboard with remediation steps.

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References

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