CVE-2023-6563

Keycloak: offline session token dos

State: Published
Severity: 7.7 High
Published: Dec 14, 2023
Updated: Sep 22, 2026
Reserved: Dec 6, 2023

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.

Scores

CVSS	Score	Vector	Source
3.1	7.7 High	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H	redhat

Weaknesses

CWE-770 Allocation of Resources Without Limits or Throttling

Affected Products

Product	Versions
Red Hat Single Sign-On 7.6 for RHEL 7Red Hat	0:18.0.11-2.redhat_00003.1.el7sso and laterNot affected
Red Hat Single Sign-On 7.6 for RHEL 8Red Hat	0:18.0.11-2.redhat_00003.1.el8sso and laterNot affected
Red Hat Single Sign-On 7.6 for RHEL 9Red Hat	0:18.0.11-2.redhat_00003.1.el9sso and laterNot affected
RHEL-8 based Middleware ContainersRed Hat	7.6-38 and laterNot affected
RHEL-8 based Middleware ContainersRed Hat	7.6.6-2 and laterNot affected
Single Sign-On 7.6.6Red Hat
Red Hat Build of KeycloakRed Hat

References

RHSA-2023:7854vendor-advisory
RHSA-2023:7855vendor-advisory
RHSA-2023:7856vendor-advisory
RHSA-2023:7857vendor-advisory
RHSA-2023:7858vendor-advisory
https://access.redhat.com/security/cve/CVE-2023-6563vdb-entry
RHBZ#2253308issue-tracking
https://github.com/keycloak/keycloak/issues/13340

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