How severe is CVE-2023-6563?

CVE-2023-6563 has a CVSS 3.x base score of 7.7, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2023-6563 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-6563?

CVE-2023-6563 primarily affects Redhat Keycloak. In total, 9 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2023-6563?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2023-6563 published?

CVE-2023-6563 was published on 2023-12-14 and last updated on 2026-06-17.

CVE-2023-6563

CVE-2023-6563 is a high-severity vulnerability in Redhat Keycloak with a CVSS 3.x base score of 7.7. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: High (CVSS 3.x base score 7.7)
EPSS exploit prediction: 1% (66th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-770
Affected product: Redhat Keycloak
Published: 2023-12-14
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2023-6563?: 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.
How severe is CVE-2023-6563?: CVE-2023-6563 has a CVSS 3.x base score of 7.7, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2023-6563 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-6563?: CVE-2023-6563 primarily affects Redhat Keycloak. In total, 9 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2023-6563?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2023-6563 published?: CVE-2023-6563 was published on 2023-12-14 and last updated on 2026-06-17.

References

Affected products (9)

cpe:2.3:a:redhat:keycloak:*:*:*:*:*:*:*:*
cpe:2.3:a:redhat:single_sign-on:7.6:*:*:*:*:*:*:*
cpe:2.3:a:redhat:single_sign-on:-:*:*:*:text-only:*:*:*
cpe:2.3:a:redhat:openshift_container_platform:4.11:*:*:*:*:*:*:*
cpe:2.3:a:redhat:openshift_container_platform:4.12:*:*:*:*:*:*:*
cpe:2.3:a:redhat:openshift_container_platform_for_power:4.9:*:*:*:*:*:*:*
cpe:2.3:a:redhat:openshift_container_platform_for_power:4.10:*:*:*:*:*:*:*
cpe:2.3:a:redhat:openshift_container_platform_for_ibm_linuxone:4.9:*:*:*:*:*:*:*
cpe:2.3:a:redhat:openshift_container_platform_for_ibm_linuxone:4.10:*:*:*:*:*:*:*

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