AI Engine < 3.6.6 - Subscriber+ Arbitrary File Read via Audio Transcription

The AI Engine WordPress plugin before 3.6.6 does not confine a caller-supplied file path before reading it and forwarding the contents to an external service, allowing users with a subscriber-level account to read arbitrary files from the server and exfiltrate them off-host. Reaching the issue at subscriber level requires a non-default public API feature to be enabled; otherwise the same issue is reachable by an administrator, which on multisite allows a non-super subsite administrator to read the network-shared configuration and its secrets.