Is CVE-2025-64763 actively exploited?

CVE-2025-64763 has no public evidence of in-the-wild exploitation as of 2025-12-05.

What is the CVSS score for CVE-2025-64763?

CVE-2025-64763 has a CVSS score of 3.7 (LOW severity). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N.

How do I patch CVE-2025-64763?

Patch guidance is available from envoyproxy security advisories. CVEDatabase generates AI-assisted remediation guidance on demand for CVE-2025-64763.

CVE-2025-64763 - remediation guidance & executive summary

Q: Which products are affected by CVE-2025-64763?

4 products: envoyproxy envoy, envoyproxy envoy, envoyproxy envoy, envoyproxy envoy.

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 Metrics

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
Attack Vector: network
Complexity: high
Privileges: none
User Action: none
Scope: unchanged
Confidentiality: low
Integrity: none
Availability: none
Weaknesses: CWE-693

Metadata

Primary Vendor: ENVOYPROXY
Published: 12/3/2025
Last Modified: 12/5/2025
Source: NIST NVD
Note: Verify all details with official vendor sources before applying patches.

Affected Products

envoyproxy : envoyenvoyproxy : envoyenvoyproxy : envoyenvoyproxy : envoy

Remediation Guidance

Executive Summary

Cite this page

CVE-2025-64763. CVEDatabase.com. Retrieved 1 May 2026. https://cvedatabase.com/cve/CVE-2025-64763

View on NIST NVD

CVE-2025-64763 vulnerability