CVE-2022-21657Network attack vector

TLS peer impersonation via ignored extended key usage

Published Feb 22, 2022 · Updated Apr 23, 2025

Improper certificate validation in affected Envoy releases allows remote authenticated users to impersonate trusted TLS peers. Envoy's TLS client and server validation paths accept a leaf or CA certificate without requiring serverAuth or clientAuth Extended Key Usage. Exploitation requires a certificate chaining to the configured trust store, such as one issued under an S/MIME-only CA, and permits an unintended peer identity to be trusted.

CVSS severity6.8
Medium
EPSS probability0.52%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper certificate validation in affected Envoy releases allows remote authenticated users to impersonate trusted TLS peers. Envoy's TLS client and server validation paths accept a leaf or CA certificate without requiring serverAuth or clientAuth Extended Key Usage. Exploitation requires a certificate chaining to the configured trust store, such as one issued under an S/MIME-only CA, and permits an unintended peer identity to be trusted.

The record

CVE
CVE-2022-21657
Published
Feb 22, 2022
Updated
Apr 23, 2025
Vendor
Envoy Proxy
Product
Envoy
Classifications
CWE-295, T1557
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 22, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 23, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.18.6
  2. Affected versionversion=>= 1.19.0, < 1.19.3
  3. Affected versionversion=>= 1.20.0, < 1.20.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Envoy Proxy · Envoyversion=< 1.18.6; version=>= 1.19.0, < 1.19.3; version=>= 1.20.0, < 1.20.2

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:P/A:N
6.8GitHub, Inc.CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo