CVE-2021-36371

LOW
3.7
CVSS Score
Published: July 9, 2021 at 08:19 PM UTC
Updated: June 17, 2026 at 03:58 AM UTC
1 product affected across 1 vendorEmissary Ingress

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Severity
LOW3.7
Exploit prediction
EPSS 0.7%

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.)

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

References (2)

x_refsource_MISCExploitThird Party Advisory
https://github.com/emissary-ingress/emissary/issues/3340
x_refsource_MISCRelease NotesThird Party Advisory
https://github.com/emissary-ingress/emissary/releases/tag/v2.0.0-ea

CVSS

Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-295

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