{"id":"CVE-2025-64763","state":"PUBLISHED","title":"Envoy forwards early CONNECT data in TCP proxy mode","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.","publishedAt":"2025-12-03T18:13:58.496Z","updatedAt":"2025-12-03T20:02:40.284Z","severity":{"score":3.7,"label":"Low","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["envoyproxy envoy"],"affected":[{"vendor":"envoyproxy","product":"envoy","versions":[{"version":">= 1.36.0, <= 1.36.2","status":"affected"},{"version":">= 1.35.0, <= 1.35.6","status":"affected"},{"version":">= 1.34.0, <= 1.34.10","status":"affected"},{"version":"<= 1.33.12","status":"affected"}]}],"references":["https://github.com/envoyproxy/envoy/security/advisories/GHSA-rj35-4m94-77jh"],"weaknesses":["CWE-693"],"ingestedAt":"2026-10-29T20:09:48.677Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/64xxx/CVE-2025-64763.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-64763","state":"PUBLISHED","datePublished":"2025-12-03T18:13:58.496Z","dateUpdated":"2025-12-03T20:02:40.284Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2025-11-10T22:29:34.876Z"},"containers":{"cna":{"title":"Envoy forwards early CONNECT data in TCP proxy mode","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"envoyproxy","product":"envoy","versions":[{"version":">= 1.36.0, <= 1.36.2","status":"affected"},{"version":">= 1.35.0, <= 1.35.6","status":"affected"},{"version":">= 1.34.0, <= 1.34.10","status":"affected"},{"version":"<= 1.33.12","status":"affected"}]}],"references":[{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-rj35-4m94-77jh","name":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-rj35-4m94-77jh","tags":["x_refsource_CONFIRM"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":3.7,"baseSeverity":"LOW","confidentialityImpact":"LOW","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-693","lang":"en","description":"CWE-693: Protection Mechanism Failure","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2025-12-03T18:13:58.496Z"},"source":{"advisory":"GHSA-rj35-4m94-77jh","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2025-12-03T19:57:09.650775Z","id":"CVE-2025-64763","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-12-03T20:02:40.284Z"}}]}}}