Denial of service in Keycloak

1) Resource exhaustion

EUVDB-ID: #VU84615

Risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-6563

CWE-ID: CWE-400 - Resource exhaustion

Exploit availability: No

Description

The vulnerability allows a remote user to perform a denial of service (DoS) attack.

The vulnerability exists due to improper control over internal resources in environments which have millions of offline tokens (> 500,000 users with each having at least 2 saved sessions). A remote user can create two or more user sessions and then open the "consents" tab of the admin User Interface, the UI attempts to load a huge number of offline client sessions leading to excessive memory and CPU consumption which could potentially crash the entire system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Keycloak: before 21.0.0

External links

http://access.redhat.com/security/cve/CVE-2023-6563
http://bugzilla.redhat.com/show_bug.cgi?id=2253308
http://github.com/keycloak/keycloak/issues/13340
http://access.redhat.com/errata/RHSA-2023:7854
http://access.redhat.com/errata/RHSA-2023:7855
http://access.redhat.com/errata/RHSA-2023:7856
http://access.redhat.com/errata/RHSA-2023:7857
http://access.redhat.com/errata/RHSA-2023:7858

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.