6.8

CVE-2022-21657: envoyproxy envoy Improper Certificate Validation

CVSS: 6.8v3.1MediumModified
Published 22-02-2022Last modified 23-04-2025
Open JSON

Vulnerability summary

CVE-2022-21657 is a medium (CVSS 6.8) Improper Certificate Validation vulnerability in envoyproxy envoy. EPSS estimates a 0.52% chance of exploitation in the next 30 days, higher than 42.8% of scored vulnerabilities.

Overall risk
27/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.8/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.52%
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. 22-02-2022
    PublishedVulnerability first disclosed.
  2. 23-04-2025
    Last modifiedVulnerability information updated.

Description

Envoy is an open source edge and service proxy, designed for cloud-native applications. In affected versions Envoy does not restrict the set of certificates it accepts from the peer, either as a TLS client or a TLS server, to only those certificates that contain the necessary extendedKeyUsage (id-kp-serverAuth and id-kp-clientAuth, respectively). This means that a peer may present an e-mail certificate (e.g. id-kp-emailProtection), either as a leaf certificate or as a CA in the chain, and it will be accepted for TLS. This is particularly bad when combined with the issue described in pull request #630, in that it allows a Web PKI CA that is intended only for use with S/MIME, and thus exempted from audit or supervision, to issue TLS certificates that will be accepted by Envoy. As a result Envoy will trust upstream certificates that should not be trusted. There are no known workarounds to this issue. Users are advised to upgrade.

CVSS metrics

3 scores · 2 sources · 2 versions

EPSS trend

Probability

0.52%

Chance of exploitation in the next 30 days

Percentile

43%

Versus all other CVEs

30-day change

0.00 pp

From 0.52% on 20-09-2026

20-09-202620-10-2026
EPSS score
0.52%

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< 1.18.6 | ≥ 1.19.0, < 1.19.3 | ≥ 1.20.0, < 1.20.2

1 vendor · 1 product

References

2 links