topic
Verified 2026-09-18

HTTP/3 and QUIC Controls

HTTP/3 maps HTTP semantics onto QUIC streams and uses its own frame, settings, and error registries.

Negotiate HTTP/3 with TLS and ALPN, enforce stream and connection limits, and treat 0-RTT requests as replayable unless the operation is safe. Do not assume HTTP/2 frame behavior applies unchanged to HTTP/3.

httpprotocolhttp3quicsecurity

Reference (http)

Alt-Svc: h3=":443"

QUIC ALPN: h3

Negotiate HTTP/3 with TLS and ALPN, enforce stream and connection limits, and treat 0-RTT requests as replayable unless the operation is safe. Do not assume HTTP/2 frame behavior applies unchanged to HTTP/3.

Common mistakes

  • Accepting replay-sensitive early data, forwarding HTTP/3-only controls as HTTP fields, or disabling migration and resource limits without understanding the deployment.
Permalink: https://merginit.com/reference/http/http3-quic-controls