Vulnerability 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.
CVSS Score
LOW
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Envoyproxy | Envoy | < 1.33.13 |
Related Weaknesses (CWE)
References
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-rj35-4m94-77jhPatchVendor Advisory
FAQ
What is CVE-2025-64763?
CVE-2025-64763 is a vulnerability with a CVSS score of 3.7 (LOW). 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 b...
How severe is CVE-2025-64763?
CVE-2025-64763 has been rated LOW with a CVSS base score of 3.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2025-64763?
Check the references section above for vendor advisories and patch information. Affected products include: Envoyproxy Envoy.