xquic — PRIORITY_UPDATE sent by the server

Inconclusive

The run did not exercise this test: the connection failed during the handshake (detected an error with protocol compliance that was not covered by more specific error codes in STREAMS_BLOCKED_BIDI: illegal frame type in handshake), so the client never reached the anomaly.

The run did not establish what this client does here — either it was never put in the situation, or its answer admits more than one reading. Not a failure, and never counted as one.

What was measured

Client

xquic — Alibaba xquic + BoringSSL, 2060a44

Test

PRIORITY_UPDATE sent by the server — h-priority-update

Clause

RFC 9218 §7.2 (MUST NOT)

Class

discretionary — The RFC permits either behaviour; the report says which was chosen.

Required behaviour

Reject it with H3_FRAME_UNEXPECTED, or ignore it — which is conformant depends on whether you implement extensible priorities at all, and that is not observable from here. A client that does implement RFC 9218 is bound by §7.2: servers "MUST NOT send PRIORITY_UPDATE frames of either type", and a client receiving one MUST treat it as a connection error of that type. A client that does not implement it sees frame type 0xf0700 as simply unknown, and RFC 9114 §9 requires unknown frame types to be ignored — so ignoring it is equally correct, for a different reason. Scoring this as a failure either way would accuse one of those two clients of a violation it did not commit, so the report says which answer was given rather than grading it.

Measured

2026-09-18

Reproduce it

The suite is the judge, so the reproduction is to point the same client at the same test and let the server report what it saw.

SESSION=$(curl -sX POST https://conformance.pqcrypta.com/session | jq -r .id)
# then drive xquic at the test URL and read the verdict:
curl -s https://conformance.pqcrypta.com/report/$SESSION.json | jq '.results["h-priority-update"]'