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CVE

CVE-2026-4634

A flaw was found in Keycloak. An unauthenticated attacker can exploit this vulnerability by sending a specially crafted

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.

HIGH · CVSS 7.5 EPSS 0.00024
Schedule remediation
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-1050Excessive Platform Resource Consumption within a Loop
▤

Affected Products & Versions

1
redhat build of keycloakall versions
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Maven org.keycloak:keycloak-services HIGH fixed in 26.5.7
▣

Scoring & Timeline

7.5
HIGH · CVSS v3.1 · secalert@redhat.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD02 Apr 2026 · 01:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

4
rhsaRHSA-2026:6478Important
rhsaRHSA-2026:6477Important
rhsaRHSA-2026:6476Important
rhsaRHSA-2026:6475Important
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://access.redhat.com/security/cve/CVE-2026-4634Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2450250Issue TrackingVendor Advisory
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