CVE-2026-67437: OliveTin: Unauthenticated DoS via OAuth2 State Memory Exhaustion (Unbounded Map Growth)

OliveTin’s OAuth2 login handler stores per-login state in an in-memory map (registeredStates) that grows unboundedly. States are added on every /oauth/login request but are never deleted or expired. An unauthenticated attacker can send millions of requests to /oauth/login to fill the map with state entries, exhausting server memory and causing a denial of service.

This is distinct from CVE-2026-28789 (concurrent map writes crash). That CVE was about the panic from unsynchronized map access — the fix added a sync.RWMutex. This vulnerability is about the unbounded growth of the map even WITH the mutex, as no cleanup mechanism exists.