Vulnerability details
CVE-2026-4634
Keycloak: keycloak: denial of service via excessive processing of openid connect scope parameters
CVSS 3.1
7.5High
Official description
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 scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 7.5High | 3.1 | CVEProject cvelistV5 (CNA) (redhat) | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 7.5High | 3.1 | CVEProject cvelistV5 (CNA) (redhat-SADP) | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| No product information recorded. | |||
References and advisories
12- https://access.redhat.com/errata/RHSA-2026:76128 vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:76129 vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:76130 vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:76132 vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:76134 vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-4634 vdb-entryx_refsource_REDHAT
- https://bugzilla.redhat.com/show_bug.cgi?id=2450250 issue-trackingx_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4634.json x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:6476 vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:6478 vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:6475 vendor-advisoryx_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:6477 vendor-advisoryx_refsource_REDHAT
Kolun on Telegram @kolunsec
Exploited CVEs, key news and a daily digest
Alerts for this product's next CVEsFollow the product to get new vulnerabilities on Telegram.
Details
- Published
- 2026-04-02
- Last updated
- 2026-10-06
- State
- Published
- Assigner (CNA)
- redhat
Exploit prediction (EPSS)
0.63%
Probability of exploitation in 30 days
50.7%
Percentile (among all CVEs)
SSVC assessment (CISA)
- Automatable
- Yes
- Exploitation
- None
- Technical impact
- Partial
Weaknesses (CWE)
- CWE-1050Excessive Platform Resource Consumption within a Loop