AIKIDO-2026-401018

TL;DR

The relay pool inserts an event id into its signature-verification cache before the verification result is known, so a first delivery whose signature check fails still records the id as seen. A malicious or compromised relay can send an event with a valid id but an invalid signature twice: the first delivery populates the cache and the second produces a cache hit that skips verification and passes the forged event to database storage. This lets unsigned events be persisted as trusted, enabling public-key impersonation or corruption of state derived from stored events. The fix performs verification before inserting into the cache so failed attempts no longer poison it.