msquic — A second control stream opened by the server

Inconclusive

The client completed its request and closed without objecting, but the anomaly was written to the control stream — a unidirectional stream nothing obliges it to read on any schedule. A one-shot request can finish before that stream is picked up, so this is equally consistent with accepting the violation and with never having seen it, and neither can be told from here.

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

msquic — .NET HttpClient + msquic, 2.7.0

Test

A second control stream opened by the server — h-second-control-stream

Clause

RFC 9114 §6.2.1 (MUST)

Class

correctness — Rejected something invalid, with the code the RFC names.

Required behaviour

Close the connection with H3_STREAM_CREATION_ERROR.

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