CVE-2026-100307

A registry member could grant their group administrator access

AWS · MCP Gateway Registry management API

First documented disclosure · Review checkpoint

Summary

The registry authenticated a group change without checking whether the caller could assign that role. An account could take administrative control of registered gateway assets.

Severity and exploitation evidence

High · 8.7/10 · CVSS 4.0. Severity source.

Exploitation not established: The reviewed advisory does not report malicious exploitation.

Exploitation evidence source

Technical severity is not a measure of observed attacks or of risk to your deployment. Attempts, demonstrations, and successful compromise retain the qualifications in the source.

How the weakness works

The registry authenticated a group change without checking whether the caller could assign that role.

Conditions required

A signed-in user could reach the external management service.

Potential impact

An account could take administrative control of registered gateway assets.

Affected versions and configurations

1.0.9 through 1.24.7.

Fix and mitigation status

1.25.0. AWS dates the release to June 27.

Practical next steps

Upgrade and review existing group grants, logs and potentially exposed credentials. The patch preserves earlier group assignments.

Operating lesson

Check the authority granted to the affected component against the operation a user expects.

Evidence and limits

The June patch predates the November public bulletin. Previously granted administrator mappings can survive the upgrade. The CVE record was published on 2026-11-11.

Sources