Jetty is a Java based web server and servlet engine. Versions 9.4.21 through 9.4.51, 10.0.15, and 11.0.15 are vulnerable to weak authentication. If a Jetty OpenIdAuthenticator uses the optional nested LoginService, and that LoginService decides to revoke an already authenticated user, then the current request will still treat the user as authenticated. The authentication is then cleared from the session and subsequent requests will not be treated as authenticated. So a request on a previously authenticated session could be allowed to bypass authentication after it had been rejected by the LoginService. This impacts usages of the jetty-openid which have configured a nested LoginService and where that LoginService will is capable of rejecting previously authenticated users. Versions 9.4.52, 10.0.16, and 11.0.16 have a patch for this issue.