CVE-2021-21378

Envoy is a cloud-native high-performance edge/middle/service proxy. In Envoy version 1.17.0 an attacker can bypass authentication by presenting a JWT token with an issuer that is not in the provider list when Envoy's JWT Authentication filter is configured with the `allow_missing` requirement under `requires_any` due to a mistake in implementation. Envoy's JWT Authentication filter can be configured with the `allow_missing` requirement that will be satisfied if JWT is missing (JwtMissed error) and fail if JWT is presented or invalid. Due to a mistake in implementation, a JwtUnknownIssuer error was mistakenly converted to JwtMissed when `requires_any` was configured. So if `allow_missing` was configured under `requires_any`, an attacker can bypass authentication by presenting a JWT token with an issuer that is not in the provider list. Integrity may be impacted depending on configuration if the JWT token is used to protect against writes or modifications. This regression was introduced on 2020/11/12 in PR 13839 which fixed handling `allow_missing` under RequiresAny in a JwtRequirement (see issue 13458). The AnyVerifier aggregates the children verifiers' results into a final status where JwtMissing is the default error. However, a JwtUnknownIssuer was mistakenly treated the same as a JwtMissing error and the resulting final aggregation was the default JwtMissing. As a result, `allow_missing` would allow a JWT token with an unknown issuer status. This is fixed in version 1.17.1 by PR 15194. The fix works by preferring JwtUnknownIssuer over a JwtMissing error, fixing the accidental conversion and bypass with `allow_missing`. A user could detect whether a bypass occurred if they have Envoy logs enabled with debug verbosity. Users can enable component level debug logs for JWT. The JWT filter logs will indicate that there is a request with a JWT token and a failure that the JWT token is missing.
Configurations

Configuration 1 (hide)

cpe:2.3:a:envoyproxy:envoy:1.17.0:*:*:*:*:*:*:*

History

24 Oct 2022, 17:11

Type Values Removed Values Added
CWE CWE-303

24 Mar 2021, 12:59

Type Values Removed Values Added
CVSS v2 : unknown
v3 : unknown
v2 : 6.4
v3 : 8.2
CPE cpe:2.3:a:envoyproxy:envoy:1.17.0:*:*:*:*:*:*:*
References (MISC) https://github.com/envoyproxy/envoy/pull/15194 - (MISC) https://github.com/envoyproxy/envoy/pull/15194 - Patch
References (MISC) https://github.com/envoyproxy/envoy/commit/ea39e3cba652bcc4b11bb0d5c62b017e584d2e5a - (MISC) https://github.com/envoyproxy/envoy/commit/ea39e3cba652bcc4b11bb0d5c62b017e584d2e5a - Patch, Third Party Advisory
References (CONFIRM) https://github.com/envoyproxy/envoy/security/advisories/GHSA-4996-m8hf-hj27 - (CONFIRM) https://github.com/envoyproxy/envoy/security/advisories/GHSA-4996-m8hf-hj27 - Mitigation, Third Party Advisory

11 Mar 2021, 03:15

Type Values Removed Values Added
New CVE

Information

Published : 2021-03-11 03:15

Updated : 2023-12-10 13:41


NVD link : CVE-2021-21378

Mitre link : CVE-2021-21378

CVE.ORG link : CVE-2021-21378


JSON object : View

Products Affected

envoyproxy

  • envoy
CWE
CWE-287

Improper Authentication

CWE-303

Incorrect Implementation of Authentication Algorithm