CVE-2023-6563

Name: CVE-2023-6563
Creator: NVD / NIST
Published: 2023-12-14T18:15:45.54+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.7/10EPSS 1.24%

Last modified Jun 17, 2026

CVE-2023-6563 is a high-severity vulnerability rated 7.7/10 on the CVSS scale. An unconstrained memory consumption vulnerability was discovered in Keycloak. It can be triggered in environments which have millions of offline tokens (> 500,000 users with each having at least 2 saved sessions). EPSS estimates a 1.24% chance of exploitation in the next 30 days.

Description

An unconstrained memory consumption vulnerability was discovered in Keycloak. It can be triggered in environments which have millions of offline tokens (> 500,000 users with each having at least 2 saved sessions). If an attacker creates 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.

Metrics

CVSS 3.1

7.7/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

EPSS Probability

1.24%

65.4th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Redhat	Keycloak	< 21.0.0
Redhat	Single Sign-On	7.6
Redhat	Single Sign-On	All versions
Redhat	Openshift Container Platform	4.11
Redhat	Openshift Container Platform	4.12
Redhat	Openshift Container Platform For Power	4.9
Redhat	Openshift Container Platform For Power	4.10
Redhat	Openshift Container Platform For Ibm Linuxone	4.9
Redhat	Openshift Container Platform For Ibm Linuxone	4.10

References

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

Timeline

Published: Dec 14, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-6563?

How severe is CVE-2023-6563?

CVE-2023-6563 has a CVSS score of 7.7/10 (HIGH severity). The EPSS model estimates a 1.24% probability of exploitation in the next 30 days.

How do I fix CVE-2023-6563?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2023-6563?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST