CVE-2022-21657

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CVE-2022-21657

Summary: X.509 Extended Key Usage and Trust Purposes bypass in Envoy

Details: 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.

References: https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/21xxx/CVE-2022-21657.json, https://github.com/envoyproxy/envoy/security/advisories/GHSA-837m-wjrv-vm5g, https://nvd.nist.gov/vuln/detail/CVE-2022-21657, https://github.com/envoyproxy/envoy/pull/630