msquic — Field line indexing a static table entry that does not exist

Fail

Rejected, but with error 0x101 where the specification requires 0x200. The violation was detected; the code reported is wrong.

The client did something the clause forbids, or failed to do what it requires.

What was measured

Client

msquic — .NET HttpClient + msquic, 2.7.0

Test

Field line indexing a static table entry that does not exist — h-qpack-static-index-invalid

Clause

RFC 9204 §3.1, §4.5.2 (MUST)

Class

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

Required behaviour

Close the connection with QPACK_DECOMPRESSION_FAILED (0x200). The static table has 99 entries, so index 200 refers to nothing, and §3.1 is explicit: "When the decoder encounters an invalid static table index in a field line representation, it MUST treat this as a connection error of type QPACK_DECOMPRESSION_FAILED." The static table needs no permission and never changes size, so unlike the dynamic-table tests this one applies to every client.

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-qpack-static-index-invalid"]'