In Eclipse Milo versions 0.6.0 through 1.1.4, OPC UA server diagnostics nodes do not enforce access authorization. An anonymous client can enable diagnostics over a None/None endpoint without a certificate; with a trusted client application certificate over SignAndEncrypt, it can read security diagnostics for other active sessions, exposing usernames, login history, authentication mechanisms, security modes and policies, and public client certificates.
CWE-862