{"cve":"CVE-2025-64763","nvd":{"published":"2025-12-03T18:15:47.037","modified":"2026-06-17T09:55:10.240","status":"Analyzed","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","score":5.3},"cwes":["CWE-693"],"references":["https://github.com/envoyproxy/envoy/security/advisories/GHSA-rj35-4m94-77jh"],"products":["envoyproxy:envoy"],"source":"nvd","synced_at":"2026-10-19T22:16:40.427100871+00:00"},"epss":{"cve":"CVE-2025-64763","score":0.00301,"percentile":0.22919,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-rj35-4m94-77jh","url":"https://osv.dev/vulnerability/GHSA-rj35-4m94-77jh","summary":"Envoy forwards early CONNECT data in TCP proxy mode","modified":"2025-12-10T20:19:27.162055Z","packages":[{"ecosystem":"Go","name":"github.com/envoyproxy/envoy","purl":"pkg:golang/github.com/envoyproxy/envoy","ranges":[">=1.36.0 <1.36.3"],"fixed":["1.36.3"]},{"ecosystem":"Go","name":"github.com/envoyproxy/envoy","purl":"pkg:golang/github.com/envoyproxy/envoy","ranges":[">=1.35.0 <1.35.7"],"fixed":["1.35.7"]},{"ecosystem":"Go","name":"github.com/envoyproxy/envoy","purl":"pkg:golang/github.com/envoyproxy/envoy","ranges":[">=1.34.0 <1.34.11"],"fixed":["1.34.11"]},{"ecosystem":"Go","name":"github.com/envoyproxy/envoy","purl":"pkg:golang/github.com/envoyproxy/envoy","ranges":["<1.33.13"],"fixed":["1.33.13"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}