CVE-2025-61926: Allstar Reviewbot has Authentication Bypass via Hard-coded Webhook Secret

A vulnerability in Allstar’s Reviewbot component caused inbound webhook requests to be validated against a hard-coded, shared secret:

https://github.com/ossf/allstar/blob/294ae985cc2facd0918e8d820e4196021aa0b914/pkg/reviewbot/reviewbot.go#L59

The value used for the secret token was compiled into the Allstar binary and could not be configured at runtime. In practice, this meant that every deployment using Reviewbot would validate requests with the same secret unless the operator modified source code and rebuilt the component - an expectation that is not documented and is easy to miss. While Reviewbot is not commonly enabled in standard Allstar setups, we are issuing this advisory to reach any environments where it may have been deployed.