{"id":"BIT-envoy-2025-64763","summary":"Envoy forwards early CONNECT data in TCP proxy mode","details":"Envoy is a high-performance edge/middle/service proxy. In 1.33.12, 1.34.10, 1.35.6, 1.36.2, and earlier, when Envoy is configured in TCP proxy mode to handle CONNECT requests, it accepts client data before issuing a 2xx response and forwards that data to the upstream TCP connection. If a forwarding proxy upstream from Envoy then responds with a non-2xx status, this can cause a de-synchronized CONNECT tunnel state. By default Envoy continues to allow early CONNECT data to avoid disrupting existing deployments. The envoy.reloadable_features.reject_early_connect_data runtime flag can be set to reject CONNECT requests that send data before a 2xx response when intermediaries upstream from Envoy may reject establishment of a CONNECT tunnel.","aliases":["CVE-2025-64763","GHSA-rj35-4m94-77jh"],"modified":"2026-09-08T08:47:31.822984351Z","published":"2025-12-06T11:38:19.488Z","database_specific":{"cpes":["cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*","cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:go:*:*"],"severity":"Medium"},"references":[{"type":"ADVISORY","url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-rj35-4m94-77jh"},{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-64763"}],"affected":[{"package":{"name":"envoy","ecosystem":"Bitnami","purl":"pkg:bitnami/envoy"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.33.13"},{"introduced":"1.34.0"},{"fixed":"1.34.11"},{"introduced":"1.35.0"},{"fixed":"1.35.7"},{"introduced":"1.36.0"},{"fixed":"1.36.3"}]}],"database_specific":{"source":"https://github.com/bitnami/vulndb/tree/main/data/envoy/BIT-envoy-2025-64763.json"},"severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N"}]}],"schema_version":"1.9.0"}