CVE-2026-33997: Moby: Off-by-one error in plugin privilege validation
Summary
A security vulnerability has been detected that allows plugins privilege validation to be bypassed during docker plugin install. Due to an error in the daemon's privilege comparison logic, the daemon may incorrectly accept a privilege set that differs from the one approved by the user.
Plugins that request exactly one privilege are also affected, because no comparison is performed at all.
Impact
If plugins are not in use, there is no impact.
When a plugin is installed, the daemon computes the privileges required by the plugin's configuration and compares them with the privileges approved during installation. A malicious plugin can exploit this bug so that the daemon accepts privileges that differ from what was intended to be approved.
Anyone who depends on the plugin installation approval flow as a meaningful security boundary is potentially impacted.
Depending on the privilege set involved, this may include highly sensitive plugin permissions such as broad device access.
For consideration: exploitation still requires a plugin to be installed from a malicious source, and Docker plugins are relatively uncommon. Docker Desktop also does not support plugins.
Workarounds
If unable to update immediately: - Do not install plugins from untrusted sources - Carefully review all privileges requested during docker plugin install - Restrict access to the Docker daemon to trusted parties, following the principle of least privilege - Avoid relying on plugin privilege approval as the only control boundary for sensitive environments
Credits
- Reported by Cody (c@wormhole.guru, PGP 0x9FA5B73E)
Other sources
Moby is an open source container framework. Prior to version 29.3.1, a security vulnerability has been detected that allows plugins privilege validation to be bypassed during docker plugin install. Due to an error in the daemon's privilege comparison logic, the daemon may incorrectly accept a privilege set that differs from the one approved by the user. Plugins that request exactly one privilege are also affected, because no comparison is performed at all. This issue has been patched in version 29.3.1.
— MITRE
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-33997?
CVE-2026-33997 has been classified as a high severity vulnerability due to its potential to allow privilege escalation.
How do I fix CVE-2026-33997?
To fix CVE-2026-33997, upgrade to the latest version of the affected software beyond 2.0.0-beta.8 or 29.3.1.
What types of software are affected by CVE-2026-33997?
CVE-2026-33997 affects specific versions of Docker and Moby packages, specifically under the versions specified.
Can CVE-2026-33997 be exploited by attackers?
Yes, CVE-2026-33997 can be exploited by attackers to bypass privilege validation during the installation of Docker plugins.
What are the implications of CVE-2026-33997 for Docker users?
The implications of CVE-2026-33997 include potential unauthorized access to system resources and risk of compromise.