Vulnerability Report

CVE-2025-64763

Title: Envoy de-synchronized CONNECT tunnel state

Other

Proof Of Concept

No public PoC currently indexed for CVE-2025-64763.

CWE Category CWE-693
Published Date Dec 03, 2025
Modified Date Dec 05, 2025
Exploit Status Not Found
Score 3.7 CVSS v3.1
Exploit Probability (EPSS)
0.29%

Vulnerability Summary

CVE-2025-64763: 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.

Impacted Vendors

E
enphase 1
E
envoyproxy 1

Reference Links

https://github.com/envoyproxy/envoy/security/advisories/GHSA-rj35-4m94-77jh
CVSS v3.1
Source Entity [email protected]
Severity LOW
3.7
Attack Vector
NETWORK
Complexity
HIGH
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS v3.1
Source Entity [email protected]
Severity MEDIUM
5.3
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2025-64763 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data or affected products updated.

MODIFIED

Vulnerability data updated via NVD.

PUBLISHED

Vulnerability first announced in NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity HIGH
Privileges N/A
Interaction NONE
CVSS Vector String CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected Stack

No specific products linked.