Security readout for executives and security teams
Plain-English summary
CVE-2026-4636 is a high-severity Keycloak authorization flaw. A logged-in user with the uma_protection role may bypass UMA policy checks and gain access to resources owned by other users. This could expose sensitive data or allow unauthorized actions in systems relying on affected Red Hat Keycloak builds for access control.
Executive priority
Prioritize remediation for internet-facing or shared Keycloak environments using UMA authorization. This is not marked as actively exploited in the provided sources, but the potential business impact is unauthorized access to protected resources, including sensitive information and privileged actions.
Technical view
The flaw affects UMA policy validation in Red Hat build of Keycloak. An authenticated user with uma_protection can include victim-owned resource identifiers in a policy creation request, despite the request path targeting an attacker-owned resource. Successful abuse can permit RPT issuance for unauthorized resources. CVSS is 8.1, with low attack complexity and high confidentiality and integrity impact.
Likely exposure
Exposure is most likely in deployments using affected Red Hat build of Keycloak 26.2 or 26.4 packages and UMA authorization features. The attacker must already be authenticated and have the uma_protection role. Systems that do not use UMA or do not grant that role broadly have lower practical exposure.
Exploitation context
The source bundle does not cite active exploitation, and KEV status is false. The issue is still serious because exploitation requires only network access, low complexity, no user interaction, and a privileged-but-plausible authenticated role. Evidence for public exploit availability is not provided in the bundle.
Researcher notes
Focus validation on authorization-server resource policy creation and role scoping. Do not assume all Keycloak deployments are affected; the provided affected list is specific to Red Hat build of Keycloak 26.2 and 26.4 packages. The bundle identifies CWE-551, but detailed root-cause code evidence is not included.
Mitigation direction
- Review RHSA-2026:6475 through RHSA-2026:6478 for the correct Red Hat update path.
- Upgrade affected Red Hat build of Keycloak packages to vendor-fixed releases.
- Restrict uma_protection role assignments to trusted accounts until updates are applied.
- Audit UMA clients and resources for unexpected policy grants or RPT issuance.
- Monitor Red Hat CVE and Bugzilla pages for revised remediation guidance.
Validation and detection
- Inventory Keycloak deployments and identify Red Hat build versions 26.2 and 26.4.
- Check installed package names against the affected package list in the CVE record.
- Confirm whether UMA authorization is enabled for protected resources.
- Review accounts granted the uma_protection role.
- After patching, verify package versions match Red Hat fixed guidance.
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-551: 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-2026-4636 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
- 8.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
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:L/UI:N/S:U/C:H/I:H/A:N2.85.2redhatCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N2.85.2redhat-SADPVulnerability scoring details
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
Base CVSS 3.1 score
8.1HighVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
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
- 2026-03-23T08:15:12.427Z: 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-2026-4636CVE reference, redhat · vdb-entry, x_refsource_REDHAT
- RHBZ#2450251CVE reference, redhat · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4636.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.
Incorrect Behavior Order: Authorization Before Parsing and Canonicalization
Incorrect Behavior Order: Authorization Before Parsing and Canonicalization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.