CVE-2025-64763 — Protection Mechanism Failure in Envoyproxy Envoy

CWE-693 — Protection Mechanism Failure5 documents5 sources
Severity
5.3MEDIUMNVD
CNA3.7
EPSS
0.0%
top 99.84%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
2
Github.com Envoyproxy EnvoyEnvoyproxy Envoy
Timeline
PublishedDec 3
Latest updateDec 5

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 existin…

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NExploitability: 3.9 | Impact: 1.4

Affected Packages3 packages

▶NVDenvoyproxy/envoy1.34.0 — 1.34.11+3
▶Gogithub.com/envoyproxy_envoy1.36.0 — 1.36.3+3
▶CVEListV5envoyproxy/envoy1.33.12+3

Patches

Patch: github.com ↗

🔴Vulnerability Details

3
OSV
Envoy forwards early CONNECT data in TCP proxy mode↗2025-12-05
▶
GHSA
Envoy forwards early CONNECT data in TCP proxy mode↗2025-12-05
▶
CVEList
Envoy forwards early CONNECT data in TCP proxy mode↗2025-12-03
▶

📋Vendor Advisories

1
Red Hat
Envoy: Envoy: De-synchronized CONNECT tunnel state due to early data handling in TCP proxy mode↗2025-12-03
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