CVE-2022-21657 | X.509 Extended Key Usage and Trust Purposes bypass in Envoy

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.

Published: 2022-02-22 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2022-21657 is rated Moderate Risk (41.1/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.50%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2022-21657

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.04% 0.50% +0.46%
2 2025-04-06 0.05% 0.04% -0.01%
3 2025-03-19 — 0.05% —

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2022-21657

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.8 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 1.6 5.2 [email protected]
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 [email protected]
4.0 2.0 MEDIUM
AV:N/AC:L/Au:S/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:S)
A single authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 8.0 2.9 [email protected]

Weakness enumeration for CVE-2022-21657

OS Trackers for CVE-2022-21657

vendor priority summary link
redhat medium — https://access.redhat.com/security/cve/CVE-2022-21657

Affected software / configurations for CVE-2022-21657

Vendor Product Version Raw CPE
envoyproxy envoy < 1.18.6 cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*
envoyproxy envoy >= 1.19.0, < 1.19.3 cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*
envoyproxy envoy >= 1.20.0, < 1.20.2 cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*

References for CVE-2022-21657

cvelogic Threat Intelligence