AUGUST 4, 2026
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Case File

CVE-2025-64763

LOW · CVSS 3.7 EPSS 0.31% Public Exploit

Source: NVD + CISA KEV + EPSS (historical backfill) · Published 2025-12-03 · Last synced 2026-08-04

CyberRota Analysis

This is a low severity vulnerability with a CVSS score of 3.7. Public exploit code or proof-of-concept references have been detected in its references.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

GitHub PoC Links

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2025-64763
Severity
LOW
CVSS
3.7
EPSS
0.31%

Original NVD 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.

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