CVE-2025-64763 - Envoy forwards early CONNECT data in TCP proxy mode

CVE ID : CVE-2025-64763 Published : Dec. 3, 2025, 6:15 p.m. | 14 minutes ago 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. Severity: 3.7 | LOW Visit the link for more details, such as CVSS details, affected products, timeline, and more...

Source: Telegram CVE Monitor