CVE-2023-6563

Keycloak: offline session token dos

HIGH
7.7
CVSS Score
Published: December 14, 2023 at 06:01 PM UTC
Updated: September 22, 2026 at 04:17 AM UTC
6 products affected across 2 vendorsOpenShift Container PlatformSingle Sign onKeycloak

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Severity
HIGH7.7
Exploit prediction
EPSS 1%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 21.0.0
Affected range stops below 21.0.0, so it looks safe — our inference, not a vendor statement
redhat-enterprise-linux (environment)
redhat-enterprise-linux (environment)
Vendor states this is fixed in 0:18.0.11-2.redhat_00003.1.el7sso (unaffected)
Vendor states this is fixed in 0:18.0.11-2.redhat_00003.1.el8sso (unaffected)
Vendor states this is fixed in 0:18.0.11-2.redhat_00003.1.el9sso (unaffected)
Vendor states this is fixed in 7.6.6 (unaffected)
redhat-enterprise-linux (environment)
All versions

CVSS

7.7HIGHredhat
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-770

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