The client completed its request and then answered nothing at all — neither a close nor an acknowledgement of the PING sent to elicit one. So this says less than the case above it: the server cannot show the question was even received, and a client that exited without closing looks from here exactly like one that read the anomaly and carried on. Reported separately rather than as silence from a live peer, which is a stronger claim than the run supports.
The suite could not establish what this client does here. That is a shortcoming of the run rather than anything about the client, and every one of these is on our list to remove.
What was measured
- Client
- xquic — Alibaba xquic + BoringSSL, 2060a44
- Test
- DATA frame before any HEADERS on the response stream —
h-data-before-headers - Clause
- RFC 9114 §4.1 (MUST)
- Class
- correctness — Rejected something invalid, with the code the RFC names.
- Required behaviour
- Close the connection with H3_FRAME_UNEXPECTED. A response begins with a field section, and §4.1 makes "receipt of an invalid sequence of frames" a connection error of that type — a body arriving before the headers that describe it is exactly that.
- Measured
- 2026-10-27
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-data-before-headers"]'