jenkins: Ephemeral user record was created on some invalid authentication attempts

A denial of service vulnerability exists in Jenkins 2.137 and earlier, 2.121.2 and earlier in BasicAuthenticationFilter.java, BasicHeaderApiTokenAuthenticator.java that allows attackers to create ephemeral in-memory user records by attempting to log in using invalid credentials...

Ephemeral user record was created on some invalid authentication attempts

When attempting to authenticate using API token, an ephemeral user record was created to validate the token in case an external security realm was used, and the user record in Jenkins not previously saved, as legacy API tokens could exist without a persisted user record. This behavior could be...