CVE-2023-6563

HIGHNVD 7.77.7—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.7 under NVD CVSS v3. EPSS exploit probability: 1.2% (68th percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
7.7EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1.2%CVSS: 7.7Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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.

CVSS v3
7.7
EG Score
7.7HIGHmedium confidence
EG Risk
40
EG Risk 40/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity77% × 45%
Exploitation1% × 40%
Automatability30% × 15%
CISA SSVC: Track at low or medium mission impact; Track or Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
1.2%
EPSS %ILE
68th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track or Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (no KEV listing, exploit record or EPSS ≥ 50%) · Automatable unknown (not published for this CVE) · Technical impact partial (CVSS below 9.0). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

December 14, 2023

Last Modified

September 22, 2026

Advisory Details (8)

Auto-updated Sep 22, 2026
Patch available. Sources: redhat.
generic

Performance Issues with many offline sessions · Issue #13340 · keycloak/keycloak · GitHub

https://github.com/keycloak/keycloak/issues/13340
redhatMentions a patch (unverified)

2253308 – (CVE-2023-6563) CVE-2023-6563 keycloak: offline session token DoS

https://bugzilla.redhat.com/show_bug.cgi?id=2253308
redhatMentions a patch (unverified)

CVE-2023-6563 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

https://access.redhat.com/security/cve/CVE-2023-6563
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2023:7858
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2023:7857
redhatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 8.

https://access.redhat.com/errata/RHSA-2023:7856
redhatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 9.

https://access.redhat.com/errata/RHSA-2023:7855
redhatMentions a patch (unverified)

Affected: Red Hat Enterprise Linux 7.

https://access.redhat.com/errata/RHSA-2023:7854

Vendor Advisories for CVE-2023-6563(5)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(5)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatrh-sso7-keycloak-0:18.0.11-2.redhat_00003.1.el7sso2023-12-14redhat
redhatrh-sso7-keycloak-0:18.0.11-2.redhat_00003.1.el8sso2023-12-14redhat
redhatrh-sso7-keycloak-0:18.0.11-2.redhat_00003.1.el9sso2023-12-14redhat
redhatrh-sso-7/sso7-rhel8-operator-bundle:7.6.6-22023-12-14redhat
redhatrh-sso7-keycloak2023-12-14redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFix by version rangeDependents
org.keycloak:keycloak-model-jpa1.0-alpha-1 ... 9.0.3 (148 versions)
  • every version up to 21.0.0: fixed in 21.0.0
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 32× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 178 total refreshes for this CVE.

  1. 2026-10-09 20:05 UTCEPSS rescore
  2. 2026-10-08 17:06 UTCEPSS rescore
  3. 2026-10-07 23:46 UTCEPSS rescore
  4. 2026-10-06 15:15 UTCEPSS rescore
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  8. 2026-10-01 19:48 UTCEPSS rescore
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  10. 2026-09-30 16:39 UTCEG score recompute
  11. 2026-09-30 15:01 UTCEPSS rescore
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  18. 2026-09-23 13:46 UTCEPSS rescore
  19. 2026-09-22 04:32 UTCVendor advisory
  20. 2026-09-22 03:32 UTCEG score recompute
  21. 2026-09-22 03:32 UTCVendor advisory
  22. 2026-09-20 20:14 UTCEPSS rescore
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  24. 2026-09-18 19:26 UTCEPSS rescore
  25. 2026-09-16 14:06 UTCEPSS rescore
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  1. 2026-09-16 05:11 UTCEPSS rescore
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  8. 2026-09-08 21:58 UTCEPSS rescore
  9. 2026-09-07 15:59 UTCEPSS rescore
  10. 2026-09-06 13:46 UTCEPSS rescore
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  13. 2026-09-04 05:04 UTCEPSS rescore
  14. 2026-09-03 10:30 UTCOSV refresh
  15. 2026-09-02 14:10 UTCEPSS rescore
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  18. 2026-08-30 19:15 UTCEPSS rescore
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  20. 2026-08-28 21:39 UTCEPSS rescore
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  23. 2026-08-25 13:47 UTCEPSS rescore
  24. 2026-08-23 00:17 UTCEPSS rescore
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  26. 2026-08-21 23:47 UTCEPSS rescore
  27. 2026-08-20 22:53 UTCEPSS rescore
  28. 2026-08-19 17:02 UTCEPSS rescore
  29. 2026-08-18 13:46 UTCEPSS rescore
  30. 2026-08-16 23:56 UTCOSV refresh
  31. 2026-08-16 14:54 UTCEPSS rescore
  32. 2026-08-16 02:12 UTCEPSS rescore
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  34. 2026-08-13 21:58 UTCEPSS rescore
  35. 2026-08-12 13:49 UTCEPSS rescore
  36. 2026-08-11 13:40 UTCEPSS rescore
  37. 2026-08-10 23:58 UTCEPSS rescore
  38. 2026-08-09 13:44 UTCEPSS rescore
  39. 2026-08-08 16:35 UTCEPSS rescore
  40. 2026-08-07 16:25 UTCEPSS rescore
  41. 2026-08-06 13:45 UTCEPSS rescore
  42. 2026-08-05 19:15 UTCEPSS rescore
  43. 2026-08-05 19:15 UTCEPSS rescore
  44. 2026-08-04 10:36 UTCEPSS rescore
  45. 2026-08-03 10:34 UTCEPSS rescore
  46. 2026-08-02 02:25 UTCEPSS rescore
  47. 2026-08-02 02:25 UTCEPSS rescore
  48. 2026-08-01 18:06 UTCOSV refresh
  49. 2026-08-01 04:14 UTCEPSS rescore
  50. 2026-07-30 16:26 UTCEPSS rescore
  51. 2026-07-30 01:29 UTCEPSS rescore
  52. 2026-07-28 15:34 UTCEPSS rescore
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  54. 2026-07-26 14:53 UTCEPSS rescore
  55. 2026-07-25 14:16 UTCEPSS rescore
  56. 2026-07-24 14:16 UTCEPSS rescore
  57. 2026-07-23 14:16 UTCEPSS rescore
  58. 2026-07-23 02:30 UTCEG score recompute
  59. 2026-07-22 23:17 UTCEG score recompute
  60. 2026-07-22 14:07 UTCEPSS rescore
  61. 2026-07-22 14:07 UTCEPSS rescore
  62. 2026-07-21 15:23 UTCEPSS rescore
  63. 2026-07-20 17:06 UTCEPSS rescore
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  68. 2026-07-16 17:01 UTCEPSS rescore
  69. 2026-07-15 16:56 UTCEPSS rescore
  70. 2026-07-15 01:59 UTCEPSS rescore
  71. 2026-07-15 01:59 UTCEPSS rescore
  72. 2026-07-15 01:10 UTCOSV refresh
  73. 2026-07-13 22:28 UTCEPSS rescore
  74. 2026-07-13 22:28 UTCEPSS rescore
  75. 2026-07-12 05:45 UTCEPSS rescore

Related CVEs(same product + same vendor + same CWE)

Same product

2 shown

Maven:org.keycloak:keycloak-model-jpa

Same vendor

2 shown

redhat:RHSA-2023:7854

Frequently asked(5)

What is CVE-2023-6563?
CVE-2023-6563 is a high vulnerability published on December 14, 2023. 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…
When was CVE-2023-6563 disclosed?
CVE-2023-6563 was first published on December 14, 2023, with the most recent update on September 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-6563 actively exploited?
CVE-2023-6563 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.2% probability of exploitation in the next 30 days (68th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2023-6563?
CVE-2023-6563 has a CVSS v3 base score of 7.7 (NVD).
How do I remediate CVE-2023-6563?
A fix for CVE-2023-6563 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2023-6563 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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