Traefik is an HTTP reverse proxy and load balancer. Versions prior to 2.11.6, 3.0.4, and 3.1.0-rc3 have a vulnerability that allows bypassing IP allow-lists via HTTP/3 early data requests in QUIC 0-RTT handshakes sent with spoofed IP addresses. Versions 2.11.6, 3.0.4, and 3.1.0-rc3 contain a patch for this issue. No known workarounds are available.