CVE-2023-6563 : Security Advisory and Response

This CVE involves an unconstrained memory consumption vulnerability in Keycloak that can lead to excessive memory and CPU consumption, potentially crashing the entire system. It affects Red Hat products such as Red Hat Single Sign-On and related versions.

Understanding CVE-2023-6563

This section provides insights into the nature of the vulnerability, its impact, technical details, affected systems, and mitigation strategies.

What is CVE-2023-6563?

CVE-2023-6563 is an unconstrained memory consumption vulnerability discovered in Keycloak. When specific conditions are met, such as having a large number of offline tokens, an attacker can trigger excessive memory and CPU consumption by creating multiple user sessions and accessing certain areas of the admin User Interface.

The Impact of CVE-2023-6563

This vulnerability poses a high severity risk, as it can potentially crash the entire system due to the overwhelming memory and CPU usage resulting from loading a significant number of offline client sessions in the UI.

Technical Details of CVE-2023-6563

Understanding the vulnerability's description, affected systems, versions, and exploitation mechanism is crucial to addressing and preventing its impact effectively.

Vulnerability Description

The vulnerability in Keycloak allows attackers to exploit the system's memory and CPU resources by generating a large number of offline client sessions, particularly through the admin User Interface.

Affected Systems and Versions

The following Red Hat products and versions are affected:

Red Hat Single Sign-On 7.6 for RHEL 7, 8, and 9
RHEL-8 based Middleware Containers
Single Sign-On 7.6.6
Red Hat Build of Keycloak

Exploitation Mechanism

To exploit this vulnerability, an attacker needs to create multiple user sessions and access the "consents" tab in the admin User Interface, triggering the excessive loading of offline client sessions, leading to a system crash.

Mitigation and Prevention

To safeguard systems from the CVE-2023-6563 vulnerability, immediate steps, long-term security practices, and patching measures are essential.

Immediate Steps to Take

Utilize a reverse proxy to block the consents URL.
Consider removing the consents application tab from the account console theme.
Disable offline user profiles entirely, although this may negatively impact end users.

Long-Term Security Practices

Implement strict session management policies, monitor resource consumption, and regularly update systems to address potential vulnerabilities proactively.

Patching and Updates

Refer to Red Hat Security Advisories such as RHSA-2023:7854, RHSA-2023:7855, and others for specific patches and updates to mitigate the CVE-2023-6563 vulnerability.

For more technical details, refer to the provided Red Hat reference and bug report.