YesWiki before 4.6.7 contains an authentication bypass vulnerability in the ActivityPub inbox that fails to bind the verified HTTP signature signer to the activity actor. Unauthenticated attackers with any ActivityPub keypair can send signed Delete or Update activities referencing a mirrored entrys sourceUrl to delete or overwrite other actors federated entries.
This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.