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.
CVE-2026-4634
“—” 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.
Also known asEUVD-2026-18212 (ENISA EUVD)Source: ENISA EUVD
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5HIGHmedium confidence
- EG Risk
- 49EG 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, 20262450250 – (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=2450250Vendor Advisories for CVE-2026-4634(9)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2026:76128Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 security update on RHEL 7
- RHSA-2026:76130Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 security update on RHEL 9
- RHSA-2026:76129Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 security update on RHEL 8
- RHSA-2026:76134Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 for OpenShift image security update
- RHSA-2026:76132Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Single Sign-On 7.6.13 security update
- RHSA-2026:6478Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat build of Keycloak 26.4.11 Images Update
- RHSA-2026:6476Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat build of Keycloak 26.2.15 Images Update
- RHSA-2026:6477Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat build of Keycloak 26.4.11 Update
- +1 more
Patch Availability(8)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| redhat | rh-sso7-keycloak-0:18.0.20-1.redhat_00001.1.el7sso | 2026-10-06 | redhat |
| redhat | rh-sso7-keycloak-0:18.0.20-1.redhat_00001.1.el8sso | 2026-10-06 | redhat |
| redhat | rh-sso7-keycloak-0:18.0.20-1.redhat_00001.1.el9sso | 2026-10-06 | redhat |
| redhat | keycloak-services | 2026-10-05 | redhat |
| redhat | rh-sso-7/sso76-openshift-rhel8:7.6-85 | 2026-10-05 | redhat |
| redhat | rhbk/keycloak-rhel9-operator:26.2-18 | 2026-04-02 | redhat |
| redhat | rhbk/keycloak-rhel9 | 2026-04-02 | redhat |
| redhat | rhbk/keycloak-rhel9-operator:26.4-14 | 2026-04-02 | redhat |
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)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| org.keycloak:keycloak-services | 1.0-alpha-1 ... 9.0.3 (223 versions) |
| — |
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.
- 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-26 21:32 UTCEG score recompute
- 2026-10-26 21:32 UTCVendor advisory
- 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
- 2026-10-25 14:25 UTCEG score recompute
- 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.9% · 58th percentile
- 2026-10-24 03:25 UTCEG score recompute
- 2026-10-24 03:25 UTCVendor advisory
- 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.9% · 58th percentile
- 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.9% · 58th percentile
- 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.9% · 58th percentile
- 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-18 03:37 UTCEG score recompute
- 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-17 13:23 UTCEG score recompute
- 2026-10-17 13:23 UTCVendor advisory
- 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.9% · 57th percentile
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- 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-12 16:03 UTCEG score recompute
- 2026-10-11 19:45 UTCEG score recompute
- 2026-10-11 17:00 UTCEG score recompute
- 2026-10-11 14:25 UTCEG score recompute
- 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.9% · 57th percentile
- 2026-10-06 17:20 UTCEG score recompute
- 2026-10-06 17:20 UTCVendor advisory
- 2026-10-06 17:13 UTCVendor advisory
- 2026-10-06 16:52 UTCEG score recompute
- 2026-10-06 16:52 UTCVendor advisory
- 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.8% · 56th percentile
- 2026-10-06 12:28 UTCEG score recompute
- 2026-10-06 12:28 UTCVendor advisory
- 2026-10-06 11:50 UTCEG score recompute
- 2026-10-06 11:50 UTCVendor advisory
- 2026-10-06 00:26 UTCEG score recompute
- 2026-10-06 00:26 UTCVendor advisory
- 2026-10-05 23:38 UTCEG score recompute
- 2026-10-05 23:38 UTCVendor advisory
- 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.7% · 51st percentile
- 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.7% · 51st percentile
- 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.7% · 51st percentile
- 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.7% · 51st percentile
- 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.7% · 51st percentile
- 2026-09-29 15:25 UTCEG score recompute
- 2026-09-29 15:25 UTCVendor advisory
- 2026-09-29 14:59 UTCEG score recompute
- 2026-09-29 14:59 UTCVendor advisory
- 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.7% · 51st percentile
- 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.7% · 51st percentile
- 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.7% · 51st percentile
- 2026-09-26 00:27 UTCEPSS rescoreEPSS 0.7% · 51st percentile
- 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
- 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-16 09:26 UTCEG score recompute
- 2026-08-16 09:26 UTCVendor advisory
- 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-14 19:01 UTCVendor advisory
- 2026-08-14 05:51 UTCEG score recompute
- 2026-08-14 05:51 UTCVendor advisory
- 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.5% · 41st percentile
- 2026-08-13 10:00 UTCVendor advisory
- 2026-08-12 20:09 UTCEG score recompute
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownMaven:org.keycloak:keycloak-services
Same vendor
10 shownredhat:RHSA-2026:76128
Frequently asked(5)
What is CVE-2026-4634?
When was CVE-2026-4634 made public?
Is CVE-2026-4634 actively exploited?
What is the CVSS score of CVE-2026-4634?
How do I remediate CVE-2026-4634?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-4634
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