critical CVSS 9

CVE-2026-54636·Docker vulnerability

Dokku is a docker-powered PaaS. Prior to 0.38.7, the cron plugin utilizes commands in the app.json file to manage system cron running as the Dokku user. An app.json cron command utilizing special shell characters - including, but not limited to, > or ; - can break out of the Docker container and execute commands on the host as the Dokku user. This vulnerability is fixed in 0.38.7.

Severity
critical
Software
Docker
Fixed in
0.38.7
Published
2026-06-26

Affected versions

Until: 0.38.7

Fixed in: 0.38.7

How to fix this CVE

Update Docker to version 0.38.7 or later to patch a critical privilege escalation vulnerability in the cron plugin. The vulnerability allows attackers with access to app.json configuration to execute arbitrary commands on the host system as the Dokku user by injecting shell metacharacters. Immediate patching is required for all Docker deployments using Dokku's cron functionality.

sudo dnf update docker-ce -y && sudo systemctl restart docker

Defensia detects this vulnerability

How to check if you are affected

  1. Run 'docker --version' and 'dokku version' to identify your current installed versions and confirm whether you are using Dokku with Docker
  2. Check all app.json files in your Dokku applications using 'find /var/lib/dokku/services -name app.json -exec grep -l cron {} \;' to identify apps with active cron job configurations
  3. Review Docker daemon logs with 'journalctl -u docker -n 500 --no-pager' and search for error messages containing shell escape attempts or unexpected command executions
  4. Verify the patch by running 'docker --version' after upgrade and confirm the version string reflects 0.38.7 or later, then restart Dokku with 'systemctl restart dokku'

FAQ

What is CVE-2026-54636?

CVE-2026-54636 is a critical privilege escalation vulnerability in Dokku's cron plugin where app.json files containing shell metacharacters (such as > or ;) can break out of container isolation and execute commands on the host system with Dokku user privileges.

Is CVE-2026-54636 being actively exploited?

No, according to CISA KEV data, CVE-2026-54636 is not currently being actively exploited in the wild. However, the critical CVSS score of 9.0 and ease of exploitation make it a high priority for patching.

What versions of Docker are affected by CVE-2026-54636?

All versions of Dokku prior to 0.38.7 are affected when Docker is deployed with Dokku's cron plugin enabled. The vulnerability exists across all distributions and Docker versions compatible with affected Dokku releases.

How do I check if my server is vulnerable to CVE-2026-54636?

Run 'dokku version' to check your Dokku version—if it is below 0.38.7, you are vulnerable. Additionally, run 'grep -r 'cron' /var/lib/dokku/*/app.json' to identify any active cron job configurations that could be exploited.

Does Defensia detect CVE-2026-54636?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Docker and Dokku are installed on a monitored server, CVE-2026-54636 will appear in your dashboard with remediation steps.

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References

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