CVE-2022-21656

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    CVE-2022-21656

    Published: 22 Feb 2022Last Modified: 12 Aug 2026

    Summary: X.509 subjectAltName matching bypass in Envoy

    Details: 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.

    References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/21xxx/CVE-2022-21656.json, https://github.com/envoyproxy/envoy/security/advisories/GHSA-c9g7-xwcv-pjx2, https://nvd.nist.gov/vuln/detail/CVE-2022-21656, https://github.com/envoyproxy/envoy/commit/bb95af848c939cfe5b5ee33c5b1770558077e64e

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- 0
    Fixed -4aaf9593152c6996b9da384c8918e9ad4f0abd4d

    Affected versions

    v1.20.1
    v1.20.0

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2022-21656 | CVE-DB