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X.509 Extended Key Usage and Trust Purposes bypass

Low
mattklein123 published GHSA-837m-wjrv-vm5g Feb 22, 2022

Package

envoy (c++)

Affected versions

1.20.1 and earlier

Patched versions

1.18.6, 1.19.3, 1.20.2

Description

CVSS Score 3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N, Low

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 #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.

Impact

Envoy will trust upstream certificates that should not be trusted.

Patches

Workarounds

None.

References

https://blog.envoyproxy.io
https://github.com/envoyproxy/envoy/releases

For more information

Open an issue in Envoy repo
Email us at envoy-security

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

CVE ID

CVE-2022-21657

Weaknesses