{"cve":"CVE-2021-36371","nvd":{"published":"2021-07-09T21:15:08.583","modified":"2026-06-17T03:58:45.800","status":"Modified","description":"Emissary-Ingress (formerly Ambassador API Gateway) through 1.13.9 allows attackers to bypass client certificate requirements (i.e., mTLS cert_required) on backend upstreams when more than one TLSContext is defined and at least one configuration exists that does not require client certificate authentication. The attacker must send an SNI specifying an unprotected backend and an HTTP Host header specifying a protected backend. (2.x versions are unaffected. 1.x versions are unaffected with certain configuration settings involving prune_unreachable_routes and a wildcard Host resource.)","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N","score":3.7},"cwes":["CWE-295"],"references":["https://github.com/emissary-ingress/emissary/issues/3340","https://github.com/emissary-ingress/emissary/releases/tag/v2.0.0-ea","https://github.com/emissary-ingress/emissary/issues/3340","https://github.com/emissary-ingress/emissary/releases/tag/v2.0.0-ea"],"products":["getambassador:emissary-ingress"],"source":"nvd","synced_at":"2026-10-19T21:21:13.713336758+00:00"},"epss":{"cve":"CVE-2021-36371","score":0.00738,"percentile":0.54548,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}