n8n before 2.29.8 and 2.30.1 Privilege Escalation via Token Exchange

n8n before 2.30.1 and 2.29.8 assigns all Public API key scopes to JWTs issued through the Token Exchange module regardless of the acting user's role. On instances where the Token Exchange feature and Public API are enabled, a low-privileged user who can obtain a valid external JWT trusted by a configured issuer can use the resulting access token to invoke administrator-only Public API operations such as role escalation, user creation, and user deletion (role escalation requires an Advanced Permissions license), and, when unverified Community Package installation is enabled, achieve remote code execution.