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Vulnerabilities

Vulnerability · CVE-2026-4634

A flaw was found in Keycloak.

Published Apr 2, 2026 · catalog updated Oct 6, 2026 · build of keycloak

Check if you run it

No confirmed exploitation is on record for CVE-2026-4634. EPSS is 0.86%. Act only if a listed version of build of keycloak is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.86%
Remediation
Advisory link
Affected products
cpe redhat/build of keycloak

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe redhat/build of keycloak26.2
  • cpe redhat/build of keycloak26.2.15
  • cpe redhat/build of keycloak26.4
  • cpe redhat/build of keycloak26.4.11

How to fix CVE-2026-4634

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-4634. EPSS is 0.86%. Act only if a listed version of build of keycloak is installed.

Which versions are affected?

Compare what you have installed with redhat/build of keycloak 26.2; redhat/build of keycloak 26.2.15; redhat/build of keycloak 26.4; redhat/build of keycloak 26.4.11. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-1050. EPSS 0.86%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 2, 2026 · NIST NVD

    Detected

    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.

  2. Oct 6, 2026 · NIST NVD

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2026-4634

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-4634

    30-day exploitation probability 0.9%

    first.org
  • NIST NVDVulnerability recordCVE-2026-4634

    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 process

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.