CVE-2025-9039

We identified an issue in the Amazon ECS agent where, under certain conditions, an introspection server could be accessed off-host by another instance if the instances are in the same security group or if their security groups allow incoming connections that include the port where the server is hosted. This issue does not affect instances where the option to allow off-host access to the introspection server is set to false.

This issue has been addressed in ECS agent version 1.97.1. We recommend upgrading to the latest version and ensuring any forked or derivative code is patched to incorporate the new fixes.

If customers cannot update to the latest AMI, they can modify the Amazon EC2 security groups to restrict incoming access to the introspection server port (51678).

Weakness

A product defines a set of insecure permissions that are inherited by objects that are created by the program.

Potential Mitigations

• Compartmentalize the system to have “safe” areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
• Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.

References

• https://aws.amazon.com/security/security-bulletins/AWS-2025-018/
• https://github.com/aws/amazon-ecs-agent/releases/tag/v1.97.1
• https://github.com/aws/amazon-ecs-agent/security/advisories/GHSA-wm7x-ww72-r77q