CVE-2026-100844 Project-MONAI CVE debrief

Who should care

Defenders responsible for MONAI deployments, especially those using nnUNetV2Runner, should assess exposure and verify configurations to prevent OS command injection. This includes operators, platform administrators, vulnerability management teams, and security teams who need to ensure that MONAI versions and configurations are secure and up-to-date.

Why it matters

Defenders should prioritize verifying MONAI versions and configurations, especially those using nnUNetV2Runner, and restrict user-controlled input to prevent OS command injection.

• Potential execution of arbitrary commands with user privileges
• Possible disruption of MONAI services and data processing
• Need for verification of MONAI versions and configurations
• Potential impact on machine learning model training and validation jobs

Technical summary

The MONAI library before version 1.6.0 is vulnerable to OS command injection in the nnUNetV2Runner component. User-controlled values taken from the YAML configuration file and from CLI/kwargs arguments are concatenated into a command string without quoting or validation and then passed to subprocess with shell=True. This allows attackers to execute arbitrary commands with the privileges of the user running the job. The vulnerability is particularly concerning because it can be exploited by loading and processing a crafted configuration file, such as through instantiating nnUNetV2Runner with malicious YAML.

Defensive priority

Defenders should prioritize verifying MONAI versions and configurations, especially those using nnUNetV2Runner, and restrict user-controlled input.

Recommended defensive actions

• Verify MONAI versions and configurations, especially those using nnUNetV2Runner
• Restrict user-controlled input to prevent OS command injection
• Update MONAI to version 1.6.0 or later
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the vulnerability in MONAI before 1.6.0. The nnUNetV2Runner component is affected, and user-controlled values are concatenated into a command string without validation.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.