Keycloak: offline session token dos (CVE-2023-6563)
Published Last modified Sources: CVE.org, OSV
What is affected, what to do
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).
Update Red Hat Single Sign-On 7.6 for RHEL 7 to version 0:18.0.11-2.redhat_00003.1.el7sso, Red Hat Single Sign-On 7.6 for RHEL 8 to version 0:18.0.11-2.redhat_00003.1.el8sso, Red Hat Single Sign-On 7.6 for RHEL 9 to version 0:18.0.11-2.redhat_00003.1.el9sso.
- Affected
- Red Hat Single Sign-On 7.6 for RHEL 7
lt *..0:18.0.11-2.redhat_00003.1.el7sso - Red Hat Single Sign-On 7.6 for RHEL 8
lt *..0:18.0.11-2.redhat_00003.1.el8sso - Red Hat Single Sign-On 7.6 for RHEL 9
lt *..0:18.0.11-2.redhat_00003.1.el9sso - Red Hat RHEL-8 based Middleware Containers
lt *..7.6-38 - Red Hat RHEL-8 based Middleware Containers
lt *..7.6.6-2
- Red Hat Single Sign-On 7.6 for RHEL 7
- Fixed in
- Red Hat Single Sign-On 7.6 for RHEL 7
0:18.0.11-2.redhat_00003.1.el7sso - Red Hat Single Sign-On 7.6 for RHEL 8
0:18.0.11-2.redhat_00003.1.el8sso - Red Hat Single Sign-On 7.6 for RHEL 9
0:18.0.11-2.redhat_00003.1.el9sso - Red Hat RHEL-8 based Middleware Containers
7.6-38 - Red Hat RHEL-8 based Middleware Containers
7.6.6-2
- Red Hat Single Sign-On 7.6 for RHEL 7
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Metrics
7.7
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
7.7
CVSS v3
Severity High on the scale from 0 to 10.
Source: CVE.org, OSV
1.2 %
EPSS score
Moderate — model estimates 1-10% exploitation likelihood.
Source: FIRST EPSS, percentile 69.0
Show all metrics
- Severity
- High
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 80.67 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 7.7 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 7.7
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 1.2 %
- Moderate — model estimates 1-10% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 69.0
- High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-770
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
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.
Source: cvelistv5, OSV (Open Source Vulnerabilities), NVD (NIST)
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| Red Hat | Red Hat Build of Keycloak |
|
|
| Red Hat | Red Hat Single Sign-On 7.6 for RHEL 7 |
|
|
| Red Hat | Red Hat Single Sign-On 7.6 for RHEL 8 |
|
|
| Red Hat | Red Hat Single Sign-On 7.6 for RHEL 9 |
|
|
| Red Hat | RHEL-8 based Middleware Containers |
|
|
| Red Hat | Single Sign-On 7.6.6 |
|
|
| redhat | keycloak |
|
|
| redhat | openshift_container_platform |
|
|
| redhat | openshift_container_platform_for_ibm_linuxone |
|
|
| redhat | openshift_container_platform_for_power |
|
|
| redhat | single_sign-on |
|
|
Vendors and products
- Red Hat Red Hat Build Of Keycloak
- Red Hat Red Hat Single Sign-on 7.6 For Rhel 7
- Red Hat Red Hat Single Sign-on 7.6 For Rhel 8
- Red Hat Red Hat Single Sign-on 7.6 For Rhel 9
- Red Hat Rhel-8 Based Middleware Containers
- Red Hat Single Sign-on 7.6.6
- Red Hat Keycloak
- Red Hat Openshift
- Red Hat Openshift Container Platform For Ibm Linuxone
- Red Hat Openshift Container Platform For Power
- Red Hat Red Hat Single Sign-On
Weakness classes (CWE)
CWE-770Allocation of Resources Without Limits or Throttling
Base
The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
Entry at MITRE CWE-770
References & sources
- NVD (NIST)vuln/detail/CVE-2023-6563advisory
- github.comkeycloak/keycloak/issues/13340web
- github.comkeycloak/keycloak/pull/15463web
- github.comkeycloak/keycloak/commit/556146f961f7c8ddf64de15e2117a58d045f72…web
- access.redhat.comRHSA-2023:7854web, Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2023:7855web, Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2023:7856web, Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2023:7857web, Vendor advisory, x_refsource_REDHAT
- access.redhat.comRHSA-2023:7858web, Vendor advisory, x_refsource_REDHAT
- access.redhat.comsecurity/cve/CVE-2023-6563web, Vulnerability database, x_refsource_REDHAT
- bugzilla.redhat.comRHBZ#2253308web, Issue tracking, x_refsource_REDHAT
- github.comkeycloak/keycloakpackage
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
Record modifiedRed Hat
Show 25 original changes
Individual changes of this event as published by NVD Type Action Before After Affected versions (publisher) added —Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2023/6xxx/CVE-2023-6563.json">CVE-2023-6563</a>Reference added —https://access.redhat.com/errata/RHSA-2023:7854Reference added —https://access.redhat.com/errata/RHSA-2023:7855Reference added —https://access.redhat.com/errata/RHSA-2023:7856Reference added —https://access.redhat.com/errata/RHSA-2023:7857Reference added —https://access.redhat.com/errata/RHSA-2023:7858Reference added —https://access.redhat.com/security/cve/CVE-2023-6563Reference added —https://bugzilla.redhat.com/show_bug.cgi?id=2253308Reference added —https://github.com/keycloak/keycloak/issues/13340Reference removed https://access.redhat.com/errata/RHSA-2023:7854—Reference removed https://access.redhat.com/errata/RHSA-2023:7855—Reference removed https://access.redhat.com/errata/RHSA-2023:7856—Reference removed https://access.redhat.com/errata/RHSA-2023:7857—Reference removed https://access.redhat.com/errata/RHSA-2023:7858—Reference removed https://access.redhat.com/security/cve/CVE-2023-6563—Reference removed https://bugzilla.redhat.com/show_bug.cgi?id=2253308—Reference removed https://github.com/keycloak/keycloak/issues/13340—Reference type removed https://access.redhat.com/errata/RHSA-2023:7854 Types: Vendor Advisory—Reference type removed https://access.redhat.com/errata/RHSA-2023:7855 Types: Vendor Advisory—Reference type removed https://access.redhat.com/errata/RHSA-2023:7856 Types: Vendor Advisory—Reference type removed https://access.redhat.com/errata/RHSA-2023:7857 Types: Exploit—Reference type removed https://access.redhat.com/errata/RHSA-2023:7858 Types: Vendor Advisory—Reference type removed https://access.redhat.com/security/cve/CVE-2023-6563 Types: Vendor Advisory—Reference type removed https://bugzilla.redhat.com/show_bug.cgi?id=2253308 Types: Issue Tracking—Reference type removed https://github.com/keycloak/keycloak/issues/13340 Types: Issue Tracking—Source identifier: secalert@redhat.com
Record modifiedCVE Program
Show 24 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://access.redhat.com/errata/RHSA-2023:7854Reference added —https://access.redhat.com/errata/RHSA-2023:7855Reference added —https://access.redhat.com/errata/RHSA-2023:7856Reference added —https://access.redhat.com/errata/RHSA-2023:7857Reference added —https://access.redhat.com/errata/RHSA-2023:7858Reference added —https://access.redhat.com/security/cve/CVE-2023-6563Reference added —https://bugzilla.redhat.com/show_bug.cgi?id=2253308Reference added —https://github.com/keycloak/keycloak/issues/13340Reference removed https://access.redhat.com/errata/RHSA-2023:7854—Reference removed https://access.redhat.com/errata/RHSA-2023:7855—Reference removed https://access.redhat.com/errata/RHSA-2023:7856—Reference removed https://access.redhat.com/errata/RHSA-2023:7857—Reference removed https://access.redhat.com/errata/RHSA-2023:7858—Reference removed https://access.redhat.com/security/cve/CVE-2023-6563—Reference removed https://bugzilla.redhat.com/show_bug.cgi?id=2253308—Reference removed https://github.com/keycloak/keycloak/issues/13340—Reference type removed https://access.redhat.com/errata/RHSA-2023:7854 Types: Vendor Advisory—Reference type removed https://access.redhat.com/errata/RHSA-2023:7855 Types: Vendor Advisory—Reference type removed https://access.redhat.com/errata/RHSA-2023:7856 Types: Vendor Advisory—Reference type removed https://access.redhat.com/errata/RHSA-2023:7857 Types: Exploit—Reference type removed https://access.redhat.com/errata/RHSA-2023:7858 Types: Vendor Advisory—Reference type removed https://access.redhat.com/security/cve/CVE-2023-6563 Types: Vendor Advisory—Reference type removed https://bugzilla.redhat.com/show_bug.cgi?id=2253308 Types: Issue Tracking—Reference type removed https://github.com/keycloak/keycloak/issues/13340 Types: Issue Tracking—Source identifier: af854a3a-2127-422b-91ae-364da2661108
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<a href="https://intel.neosec.eu/en/cve/CVE-2023-6563"><img src="https://intel.neosec.eu/badge/cve/CVE-2023-6563.svg?lang=en" alt="CVE-2023-6563 – NEOSEC Intel" height="20"></a>