LiveActive security incident?Get immediate response
CVE Record

CVE-2026-4634: Keycloak: keycloak: denial of service via excessive processing of openid connect scope parameters

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.

HighCVSS 7.5Not KEV-listedUpdated
Discuss exposureBack to CVEs
Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-1050: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-4634 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
7Timeline events
2ADP providers
13Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-4634Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. ADP timelineredhat-SADP

    Reported to Red Hat.

  2. Source timelineredhat

    Reported to Red Hat.

  3. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  4. ADP timelineredhat-SADP

    Made public.

  5. Source timelineredhat

    Made public.

  6. CVE publishedCVE Program

    The CVE record was published.

  7. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPkeycloak: Keycloak: Denial of Service via excessive processing of OpenID Connect scope parameters
other:Red Hat severity ratingcvssV3_1
  • 2026-03-23T08:40:02.817Z: Reported to Red Hat.
  • 2026-04-02T12:30:00.000Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Red HatRed Hat build of Keycloak 26.2rhbk/keycloak-operator-bundle, 26.2.15-1affected
Red HatRed Hat build of Keycloak 26.2rhbk/keycloak-rhel9, 26.2-18affected
Red HatRed Hat build of Keycloak 26.2rhbk/keycloak-rhel9-operator, 26.2-18affected
Red HatRed Hat build of Keycloak 26.2.15rhbk/keycloak-rhel9unaffected
Red HatRed Hat build of Keycloak 26.4rhbk/keycloak-operator-bundle, 26.4.11-1affected
Red HatRed Hat build of Keycloak 26.4rhbk/keycloak-rhel9, 26.4-14affected
Red HatRed Hat build of Keycloak 26.4rhbk/keycloak-rhel9-operator, 26.4-14affected
Red HatRed Hat build of Keycloak 26.4.11rhbk/keycloak-rhel9unaffected
Red HatRed Hat Single Sign-On 7.6.13keycloak-servicesunaffected
Red HatRed Hat Single Sign-On 7.6 for RHEL 7rh-sso7-keycloak, 0:18.0.20-1.redhat_00001.1.el7ssoaffected
Red HatRed Hat Single Sign-On 7.6 for RHEL 8rh-sso7-keycloak, 0:18.0.20-1.redhat_00001.1.el8ssoaffected
Red HatRed Hat Single Sign-On 7.6 for RHEL 9rh-sso7-keycloak, 0:18.0.20-1.redhat_00001.1.el9ssoaffected
Red HatRHEL-8 based Middleware Containersrh-sso-7/sso76-openshift-rhel8, 7.6-85affected
Weakness

CWE details

CWE-1050

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-1050 · source CWE mapping

Excessive Platform Resource Consumption within a Loop

Excessive Platform Resource Consumption within a Loop represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs