#VU77766 Improper certificate validation in Keycloak - CVE-2023-2422

Vulnerability identifier: #VU77766

Vulnerability risk: Medium

CVSSv4.0: 5 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2023-2422

CWE-ID: CWE-295

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Keycloak
Server applications / Directory software, identity management

Vendor: Keycloak

Description

The vulnerability allows a remote user to bypass authorization process.

The vulnerability exists due to improper certificate validation chain when a Keycloak server is configured to support mTLS authentication for OAuth/OpenID clients. A remote user that possesses a proper certificate can authorize itself as any other client and therefore access data that belongs to other clients.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Keycloak: 10.0.0 - 19.0.3, 20.0.0 - 21.1.1

---

External links
https://github.com/keycloak/keycloak/security/advisories/GHSA-3qh5-qqj2-c78f

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.