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CVE-2025-64763
Good to know:
Date: December 3, 2025
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.
Severity Score
Severity Score
Weakness Type (CWE)
Protection Mechanism Failure
CWE-693Top Fix
Upgrade Version
Upgrade to version github.com/envoyproxy/envoy - v1.36.3;github.com/envoyproxy/envoy - v1.35.7;github.com/envoyproxy/envoy - v1.34.11;github.com/envoyproxy/envoy - v1.33.13;https://github.com/envoyproxy/envoy.git - v1.33.13;https://github.com/envoyproxy/envoy.git - v1.34.11;https://github.com/envoyproxy/envoy.git - v1.35.7;https://github.com/envoyproxy/envoy.git - v1.36.3
CVSS v3.1
| Base Score: |
|
|---|---|
| Attack Vector (AV): | NETWORK |
| Attack Complexity (AC): | HIGH |
| Privileges Required (PR): | NONE |
| User Interaction (UI): | NONE |
| Scope (S): | UNCHANGED |
| Confidentiality (C): | LOW |
| Integrity (I): | NONE |
| Availability (A): | NONE |