CVE-2026-4634

HIGHPre-NVD 7.57.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6% (49th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Trending — 3 sources updated this week

Also known asEUVD-2026-18212 (ENISA EUVD)Source: ENISA EUVD

7.5EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

A flaw was found in Keycloak. An unauthenticated attacker can exploit this vulnerability by sending a specially crafted POST request with an excessively long scope parameter to the OpenID Connect (OIDC) token endpoint. This leads to high resource consumption and prolonged processing times, ultimately resulting in a Denial of Service (DoS) for the Keycloak server.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.6% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
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
0.6%
EPSS %ILE
49th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-26). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; 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 (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

April 2, 2026

Last Modified

October 26, 2026

Advisory Details (6)

Auto-updated Jul 3, 2026
Patch available. Sources: redhat.
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:6478
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:6477
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:6476
Red HatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:6475
Red Hat

2450250 – (CVE-2026-4634) CVE-2026-4634 keycloak: Keycloak: Denial of Service via excessive processing of OpenID Connect scope parameters

https://bugzilla.redhat.com/show_bug.cgi?id=2450250
Red HatMentions a patch (unverified)

cve-details

https://access.redhat.com/security/cve/CVE-2026-4634

Patch Availability(8)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatrh-sso7-keycloak-0:18.0.20-1.redhat_00001.1.el7sso2026-10-06redhat
redhatrh-sso7-keycloak-0:18.0.20-1.redhat_00001.1.el8sso2026-10-06redhat
redhatrh-sso7-keycloak-0:18.0.20-1.redhat_00001.1.el9sso2026-10-06redhat
redhatkeycloak-services2026-10-05redhat
redhatrh-sso-7/sso76-openshift-rhel8:7.6-852026-10-05redhat
redhatrhbk/keycloak-rhel9-operator:26.2-182026-04-02redhat
redhatrhbk/keycloak-rhel92026-04-02redhat
redhatrhbk/keycloak-rhel9-operator:26.4-142026-04-02redhat

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-services1.0-alpha-1 ... 9.0.3 (223 versions)
  • every version up to 26.5.7: fixed in 26.5.7
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 53× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 237 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 137 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  2. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  3. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  4. 2026-10-26 21:32 UTCEG score recompute
  5. 2026-10-26 21:32 UTCVendor advisory
  6. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  7. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  8. 2026-10-25 14:25 UTCEG score recompute
  9. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  10. 2026-10-24 03:25 UTCEG score recompute
  11. 2026-10-24 03:25 UTCVendor advisory
  12. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  13. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  14. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.9% · 58th percentile
  15. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  16. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  17. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  18. 2026-10-18 03:37 UTCEG score recompute
  19. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  20. 2026-10-17 13:23 UTCEG score recompute
  21. 2026-10-17 13:23 UTCVendor advisory
  22. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  23. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  24. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  25. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.9% · 57th percentile
Show 75 more
  1. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  2. 2026-10-12 16:03 UTCEG score recompute
  3. 2026-10-11 19:45 UTCEG score recompute
  4. 2026-10-11 17:00 UTCEG score recompute
  5. 2026-10-11 14:25 UTCEG score recompute
  6. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  7. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  8. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  9. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  10. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.9% · 57th percentile
  11. 2026-10-06 17:20 UTCEG score recompute
  12. 2026-10-06 17:20 UTCVendor advisory
  13. 2026-10-06 17:13 UTCVendor advisory
  14. 2026-10-06 16:52 UTCEG score recompute
  15. 2026-10-06 16:52 UTCVendor advisory
  16. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  17. 2026-10-06 12:28 UTCEG score recompute
  18. 2026-10-06 12:28 UTCVendor advisory
  19. 2026-10-06 11:50 UTCEG score recompute
  20. 2026-10-06 11:50 UTCVendor advisory
  21. 2026-10-06 00:26 UTCEG score recompute
  22. 2026-10-06 00:26 UTCVendor advisory
  23. 2026-10-05 23:38 UTCEG score recompute
  24. 2026-10-05 23:38 UTCVendor advisory
  25. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  26. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  27. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  28. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  29. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  30. 2026-09-29 15:25 UTCEG score recompute
  31. 2026-09-29 15:25 UTCVendor advisory
  32. 2026-09-29 14:59 UTCEG score recompute
  33. 2026-09-29 14:59 UTCVendor advisory
  34. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  35. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  36. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  37. 2026-09-26 00:27 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  38. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  39. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  40. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  41. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  42. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  43. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  44. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  45. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  46. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  47. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  48. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  49. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  50. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  51. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  52. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  53. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  54. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  55. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  56. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  57. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  58. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  59. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  60. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  61. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  62. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  63. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  64. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  65. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  66. 2026-08-16 09:26 UTCEG score recompute
  67. 2026-08-16 09:26 UTCVendor advisory
  68. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  69. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  70. 2026-08-14 19:01 UTCVendor advisory
  71. 2026-08-14 05:51 UTCEG score recompute
  72. 2026-08-14 05:51 UTCVendor advisory
  73. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  74. 2026-08-13 10:00 UTCVendor advisory
  75. 2026-08-12 20:09 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-4634?
CVE-2026-4634 is a high-severity vulnerability; its CVE record was published on April 2, 2026. A flaw was found in Keycloak. An unauthenticated attacker can exploit this vulnerability by sending a specially crafted POST request with an excessively long scope parameter to the OpenID Connect (OIDC) token endpoint. This leads to high resource consumption and prolonged processing times,…
When was CVE-2026-4634 made public?
CVE-2026-4634 was made public on April 2, 2026: that is the date its CVE record's CNA, Red Hat, Inc., gives for when the vulnerability was made public. The CVE record itself was published on April 2, 2026. EchelonGraph's copy of the record carries a last-modified date of October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-4634 actively exploited?
CVE-2026-4634 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (49th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-4634?
CVE-2026-4634 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-4634?
A fix for CVE-2026-4634 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-4634 are linked in the Vendor Advisories panel on this page.

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