Security readout for executives and security teams
Plain-English summary
Keycloak can be made unavailable by an unauthenticated request that abuses an overly long OIDC scope value. The impact is service disruption, not data theft or privilege escalation. Organizations using affected Red Hat build of Keycloak 26.2 or 26.4 packages should treat this as an availability risk for login and identity services.
Executive priority
High priority for environments where Keycloak supports authentication for critical applications. A successful attack could interrupt login and access flows without needing credentials. Remediate during the next urgent patch window, faster for externally reachable deployments.
Technical view
The flaw affects the OIDC token endpoint, where excessive processing of long scope parameters can consume resources and cause prolonged processing. CVSS 3.1 is 7.5: network reachable, low complexity, no privileges or user interaction, with high availability impact only. Red Hat lists affected and unaffected package states for 26.2 and 26.4 streams.
Likely exposure
Exposure is most likely where Red Hat build of Keycloak token endpoints are reachable by untrusted clients. The source bundle identifies affected rhbk/keycloak-rhel9, operator, and operator-bundle packages in 26.2 and 26.4 streams.
Exploitation context
The bundle describes unauthenticated remote DoS potential but does not cite active exploitation. KEV status is false. No exploit maturity, public proof-of-concept status, or observed attack campaign is provided in the supplied sources.
Researcher notes
Evidence is strongest for Red Hat build packaging and OIDC token endpoint behavior. The bundle does not provide root-cause code detail, exploit samples, or complete fixed-version mapping for every package. Avoid assuming upstream Keycloak or non-Red Hat distributions are affected unless vendor data confirms it.
Mitigation direction
- Apply the relevant Red Hat advisories RHSA-2026:6475 through RHSA-2026:6478.
- Verify exact fixed package versions in Red Hat guidance before upgrading.
- Prioritize internet-facing or partner-facing Keycloak deployments first.
- Check vendor guidance if immediate patching is not possible.
- Monitor identity-service capacity and errors during remediation.
Validation and detection
- Inventory Red Hat build of Keycloak 26.2 and 26.4 deployments.
- Compare installed rhbk/keycloak-rhel9 and operator packages against affected entries.
- Confirm token endpoints are not unnecessarily exposed to untrusted networks.
- Review logs and metrics for unusual token endpoint resource spikes.
- Document patched versions and residual exposure after remediation.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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-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 lookupCredential 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 lookupCVE-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- 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
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.
SSVC decision data
CVSS vector scores
2 official scoresWe 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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhatCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- ADP timelineredhat-SADP
Reported to Red Hat.
- Source timelineredhat
Reported to Red Hat.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- Source timelineredhat
Made public.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-03-23T08:40:02.817Z: Reported to Red Hat.
- 2026-04-02T12:30:00.000Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- RHSA-2026:6475CVE reference, redhat · vendor-advisory, x_refsource_REDHAT
- RHSA-2026:6476CVE reference, redhat · vendor-advisory, x_refsource_REDHAT
- RHSA-2026:6477CVE reference, redhat · vendor-advisory, x_refsource_REDHAT
- RHSA-2026:6478CVE reference, redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-4634CVE reference, redhat · vdb-entry, x_refsource_REDHAT
- RHBZ#2450250CVE reference, redhat · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4634.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
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.