Staging Environment: Content and features may be unstable or change without notice.
Advisory details: vulnrichment / CVE-2026-4634
Advisory ID vulnrichment/CVE-2026-4634
Aliases
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 0.0
Risk
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (1)
CWE-1050 Excessive Platform Resource Consumption within a Loop
System Score Found at
cvssv3.1 7.5
ssvc Track
Reference id Reference type URL
https://access.redhat.com/errata/RHSA-2026:6475
https://access.redhat.com/errata/RHSA-2026:6476
https://access.redhat.com/errata/RHSA-2026:76128
https://access.redhat.com/errata/RHSA-2026:76129
https://access.redhat.com/errata/RHSA-2026:76130
https://access.redhat.com/errata/RHSA-2026:76132
https://access.redhat.com/errata/RHSA-2026:76134
https://access.redhat.com/security/cve/CVE-2026-4634
https://bugzilla.redhat.com/show_bug.cgi?id=2450250
cpe:/a:redhat:build_keycloak:26.2::el9 Other https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:/a:redhat:build_keycloak:26.2::el9
cpe:/a:redhat:build_keycloak:26.4::el9 Other https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:/a:redhat:build_keycloak:26.4::el9
cpe:/a:redhat:red_hat_single_sign_on:7.6 Other https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:/a:redhat:red_hat_single_sign_on:7.6
cpe:/a:redhat:red_hat_single_sign_on:7.6::el7 Other https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:/a:redhat:red_hat_single_sign_on:7.6::el7
cpe:/a:redhat:red_hat_single_sign_on:7.6::el8 Other https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:/a:redhat:red_hat_single_sign_on:7.6::el8
cpe:/a:redhat:red_hat_single_sign_on:7.6::el9 Other https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:/a:redhat:red_hat_single_sign_on:7.6::el9
cpe:/a:redhat:rhosemc:1.0::el8 Other https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:/a:redhat:rhosemc:1.0::el8
RHSA-2026:6477 Advisory https://access.redhat.com/errata/RHSA-2026:6477
RHSA-2026:6478 Advisory https://access.redhat.com/errata/RHSA-2026:6478
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at None
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2026-04-03T17:22:51Z/ Found at None

There are no SSVC decisions available.