The Trailer Frame Bug Class: RFC 9114 §4.1 as a Universal HTTP/3 State Machine Attack Surface
Sending an RFC 9114 §4.1 trailer HEADERS frame to production HTTP/3 infrastructure triggers state machine failures across two independent CDN edge implementations and the quiche client library. Server-side: 60-second goroutine hang (CDN-A) and 12,200ms QPACK decoder stall with 24.9× worker amplification (CDN-B). Client-side: permanent zombie stream leak in quiche driving Network Service memory from 6 MB to 339 MB before OOM. All three share the same root cause: the second HEADERS frame on a request stream reaches a code path with no defined handler. The threat model inversion — server pushing a malformed trailer toward client — transforms a server-side bug class into a drive-by browser memory exhaustion attack.
