Analyst readout for executives and security teams
Plain-English summary
This Keycloak flaw lets a logged-in low-privilege user trigger an authentication fallback that can grant the client service account's permissions. Business risk depends on how powerful those service accounts are. The source bundle does not name a fixed version or active exploitation.
Executive priority
Prioritize review this week for environments where Keycloak service accounts can access sensitive data or administrative functions. The CVSS is medium, but privilege escalation to over-permissioned service accounts can create high business impact.
Technical view
The TokenEndpoint mishandles an oversized subject_token JWT. When the token exceeds a 4000-character limit, it is silently dropped and processing falls back to client credentials, allowing privilege escalation to the client's service account. Red Hat maps this to CWE-1284 and CVSS 6.8.
Likely exposure
Exposure is limited to Red Hat Build of Keycloak deployments, specifically the rhbk/keycloak-rhel9 package listed as affected. The bundle provides no affected version range, so teams should treat installed Red Hat Build of Keycloak instances as requiring vendor verification.
Exploitation context
The attack requires an authenticated low-privilege user and high attack complexity. No KEV listing or cited source in the bundle supports active exploitation. Impact can be serious where client service accounts hold broad permissions.
Researcher notes
Evidence supports a logic/validation failure around subject_token size handling and fallback behavior. The source bundle does not provide fixed versions, affected version ranges, public exploit status, or vendor workaround details beyond the Red Hat references.
Mitigation direction
- Check Red Hat guidance for fixed builds or official workarounds.
- Inventory Red Hat Build of Keycloak rhbk/keycloak-rhel9 deployments.
- Reduce service-account permissions for affected clients where business-safe.
- Limit TokenEndpoint access to trusted authenticated clients where feasible.
- Monitor vendor advisories for version-specific remediation details.
Validation and detection
- Confirm whether deployed Keycloak builds match Red Hat Build of Keycloak.
- Review clients with enabled service accounts and elevated permissions.
- Check authentication logs for abnormal TokenEndpoint requests with oversized subject_token values.
- Track Red Hat CVE and Bugzilla updates for affected version details.
- Verify compensating controls do not break required authentication flows.
Public sources used
Based on public source material and reviewed before publication.
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-1284: 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 lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-9704 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
- Medium
- CVSS
- 6.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/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
1 official scoreWe 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:H/PR:L/UI:N/S:U/C:H/I:H/A:N 1.6 5.2 redhat Vulnerability scoring details
Base CVSS 3.1 score
6.8 MediumVector: CVSS:3.1/AV:N/AC:H/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.
- Source timeline redhat
Reported to Red Hat.
- CVE reserved CVE Program
The CVE ID was reserved by the assigning CNA.
- Source timeline redhat
Made public.
- CVE published CVE Program
The CVE record was published.
- CVE updated CVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 source CVE List V5
- https://access.redhat.com/security/cve/CVE-2026-9704 CVE reference, redhat · vdb-entry, x_refsource_REDHAT
- RHBZ#2481877 CVE reference, redhat · issue-tracking, x_refsource_REDHAT
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.
CWE mapping pending import
This CVE carries a CWE mapping that will resolve to a full Glexia CWE intelligence page after the official CWE import is complete.