How severe is CVE-2022-21656?

CVE-2022-21656 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2022-21656 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2022-21656?

CVE-2022-21656 affects Envoyproxy Envoy. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2022-21656?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2022-21656 published?

CVE-2022-21656 was published on 2022-02-22 and last updated on 2026-06-17.

CVE-2022-21656

CVE-2022-21656 is a high-severity vulnerability in Envoyproxy Envoy with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-843.

Key facts

Severity: High (CVSS 3.x base score 7.4)
CVSS v2: 5.8
EPSS exploit prediction: 1% (51st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-843
Affected product: Envoyproxy Envoy
Published: 2022-02-22
Last modified: 2026-06-17

Description

Envoy is an open source edge and service proxy, designed for cloud-native applications. The default_validator.cc implementation used to implement the default certificate validation routines has a "type confusion" bug when processing subjectAltNames. This processing allows, for example, an rfc822Name or uniformResourceIndicator to be authenticated as a domain name. This confusion allows for the bypassing of nameConstraints, as processed by the underlying OpenSSL/BoringSSL implementation, exposing the possibility of impersonation of arbitrary servers. As a result Envoy will trust upstream certificates that should not be trusted.

Frequently asked questions

What is CVE-2022-21656?: Envoy is an open source edge and service proxy, designed for cloud-native applications. The default_validator.cc implementation used to implement the default certificate validation routines has a "type confusion" bug when processing subjectAltNames. This processing allows, for example, an rfc822Name or uniformResourceIndicator to be authenticated as a domain name. This confusion allows for the bypassing of nameConstraints, as processed by the underlying OpenSSL/BoringSSL implementation, exposing the possibility of impersonation of arbitrary servers. As a result Envoy will trust upstream certificates that should not be trusted.
How severe is CVE-2022-21656?: CVE-2022-21656 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2022-21656 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (51st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2022-21656?: CVE-2022-21656 affects Envoyproxy Envoy. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2022-21656?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2022-21656 published?: CVE-2022-21656 was published on 2022-02-22 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*

More vulnerabilities in Envoyproxy Envoy

CVE-2022-29226 — Critical (CVSS 10.0): Envoy is a cloud-native high-performance proxy. In versions prior to 1.22.1 the OAuth filter implementation does not…
CVE-2019-18802 — Critical (CVSS 9.8): An issue was discovered in Envoy 1.12.0. An untrusted remote client may send an HTTP header (such as Host) with…
CVE-2019-18801 — Critical (CVSS 9.8): An issue was discovered in Envoy 1.12.0. An untrusted remote client may send HTTP/2 requests that write to the heap…
CVE-2020-35470 — High (CVSS 8.8): Envoy before 1.16.1 logs an incorrect downstream address because it considers only the directly connected peer, not the…
CVE-2024-23324 — High (CVSS 8.6): Envoy is a high-performance edge/middle/service proxy. External authentication can be bypassed by downstream…
CVE-2023-35941 — High (CVSS 8.6): Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.27.0,…

All CVEs affecting Envoyproxy Envoy →

Other CWE-843 vulnerabilities

CVE-2021-33970 — Critical (CVSS 10.0): Buffer Overflow vulnerability in Qihoo 360 Chrome v13.0.2170.0 allows attacker to escalate priveleges.
CVE-2010-2299 — Critical (CVSS 10.0): The Clipboard::DispatchObject function in app/clipboard/clipboard.cc in Google Chrome before 5.0.375.70 does not…
CVE-2023-22579 — Critical (CVSS 9.9): Due to improper parameter filtering in the sequalize js library, can a attacker peform injection.
CVE-2026-13776 — Critical (CVSS 9.8): Type Confusion in Dawn in Google Chrome prior to 150.0.7871.47 allowed a remote attacker who had compromised the…
CVE-2026-43038 — Critical (CVSS 9.8): In the Linux kernel, the following vulnerability has been resolved: ipv6: icmp: clear skb2->cb[] in…
CVE-2025-70023 — Critical (CVSS 9.8): An issue pertaining to CWE-843: Access of Resource Using Incompatible Type was discovered in transloadit uppy v0.25.6.

Browse all CWE-843 vulnerabilities →