CVE-2025-26620: Duende.AccessTokenManagement race condition when concurrently retrieving customized Client Credentials Access Tokens

Duende.AccessTokenManagement contains a race condition when requesting access tokens using the client credentials flow. Concurrent requests to obtain an access token using differing protocol parameters can return access tokens obtained with the wrong scope, resource indicator, or other protocol parameters. Such usage is somewhat atypical, and only a small percentage of users are likely to be affected.