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.
Metrics
Affected Vendors & Products
References
History
Fri, 05 Dec 2025 17:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| CPEs | cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* |
Thu, 04 Dec 2025 16:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Envoyproxy
Envoyproxy envoy |
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| Vendors & Products |
Envoyproxy
Envoyproxy envoy |
Wed, 03 Dec 2025 20:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
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Wed, 03 Dec 2025 18:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Envoy forwards early CONNECT data in TCP proxy mode | |
| Weaknesses | CWE-693 | |
| References |
| |
| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published: 2025-12-03T18:13:58.496Z
Updated: 2025-12-03T20:02:40.284Z
Reserved: 2025-11-10T22:29:34.876Z
Link: CVE-2025-64763
Updated: 2025-12-03T20:02:32.968Z
Status : Analyzed
Published: 2025-12-03T18:15:47.037
Modified: 2025-12-05T16:52:24.367
Link: CVE-2025-64763
No data.