5.3

CVE-2025-64763: envoyproxy envoy Protection Mechanism Failure

CVSS: 5.3v3.1MediumAnalyzed
AliasesGHSA-rj35-4m94-77jhBIT-envoy-2025-64763
Published 03-12-2025Last modified 03-12-2025
Open JSON

Vulnerability summary

CVE-2025-64763 is a medium (CVSS 5.3) Protection Mechanism Failure vulnerability in envoyproxy envoy. EPSS estimates a 0.30% chance of exploitation in the next 30 days, higher than 21.5% of scored vulnerabilities.

Overall risk
21/100
0100
Low · default modelHow is this calculated?
CVSS score
5.3/10
010
Medium · v3.1 (NVD)
EPSS score
0.30%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 03-12-2025
    PublishedVulnerability first disclosed.
  2. 03-12-2025
    Last modifiedVulnerability information updated.

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

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.30%

Chance of exploitation in the next 30 days

Percentile

22%

Versus all other CVEs

30-day change

0.00 pp

From 0.30% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.30%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Envoyproxy1 product
  • envoy≥ 1.36.0, ≤ 1.36.2 | ≥ 1.35.0, ≤ 1.35.6 | ≥ 1.34.0, ≤ 1.34.10 | ≤ 1.33.12 | < 1.33.13 | ≥ 1.34.0, < 1.34.11 | ≥ 1.35.0, < 1.35.7 | ≥ 1.36.0, < 1.36.3
Github.com/envoyproxy1 product
  • envoy≥ 1.36.0, < 1.36.3 | ≥ 1.35.0, < 1.35.7 | ≥ 1.34.0, < 1.34.11 | < 1.33.13

2 vendors · 2 products

References

3 links