CVE-2025-64763
Published: Dec 3, 2025
Modified: Dec 3, 2025
CVSS v3.1
3.7
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.
| Vendor | Product | Versions |
|---|---|---|
envoyproxy | envoy | affected >= 1.36.0, <= 1.36.2affected >= 1.35.0, <= 1.35.6affected >= 1.34.0, <= 1.34.10affected <= 1.33.12 |
Weaknesses (CWE)
CVSS v3.1 Details
CVSS v3.1 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
References
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