Allocation of Resources Without Limits in Keycloak

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2023-6563: 1.24% estimated exploitation activity in the next 30 days; percentile 69.18 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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.

Published by the source

14 Dec 2023, 18:30 UTC

Last modified by the source

29 Dec 2023, 00:14 UTC

Source last checked

26 Oct 2026, 16:24 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-54f3-c6hg-865h

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# Patch Next advisory brief: CVE-2023-6563

Advisory: Allocation of Resources Without Limits in Keycloak
IDs: CVE-2023-6563, GHSA-54f3-c6hg-865h
Record: https://patchnext.com/advisories/cve-2023-6563 (revision 1, source checked 26 Oct 2026, 16:24 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.keycloak:keycloak-model-jpa 21.0.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.keycloak:keycloak-model-jpa: affected < 21.0.0; fixed in 21.0.0

## Suggested inspection (read-only)
- Maven org.keycloak:keycloak-model-jpa: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.keycloak:keycloak-model-jpa.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-54f3-c6hg-865h (GitHub-reviewed advisory GHSA-54f3-c6hg-865h lists affected ranges: Maven org.keycloak:keycloak-model-jpa >=0 <21.0.0)

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