Keycloak: keycloak: privilege escalation due to oversized subject_token jwt
Priority MEDIUM 40CWE-1284Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA, GitHub and Red Hat.
Summary
A flaw was found in Keycloak. An authenticated user with low privileges can exploit this vulnerability by sending an oversized subject_token JSON Web Token (JWT) to the TokenEndpoint. When the token exceeds a 4000-character limit, it is silently dropped, causing the system to fall back to client credentials. This allows the user to gain the permissions of the client's service account, leading to privilege escalation.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0032 25th percentileScored 2026-11-07
Fix Fixed org.keycloak:keycloak-server-spi-private (Maven): 26.6.3org.keycloak:keycloak-services (Maven): 26.6.3Red Hat: 4 advisories
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Red Hat | Red Hat build of Keycloak 26.4 | — | 26.4.13-1 | Patch available | CNA |
| Red Hat | Red Hat build of Keycloak 26.4 | — | 26.4-19 | Patch available | CNA |
| Red Hat | Red Hat build of Keycloak 26.4 | — | 26.4-19 | Patch available | CNA |
| Red Hat | Red Hat build of Keycloak 26.4.13 | — | — | Not affected | CNA |
| Red Hat | Red Hat build of Keycloak 26.6 | — | 26.6.3-3 | Patch available | CNA |
| Red Hat | Red Hat build of Keycloak 26.6 | — | 26.6-6 | Patch available | CNA |
| Red Hat | Red Hat build of Keycloak 26.6 | — | 26.6-6 | Patch available | CNA |
| Red Hat | Red Hat build of Keycloak 26.6.3 | — | — | Not affected | CNA |
| — | org.keycloak:keycloak-server-spi-private (Maven) | before 26.6.3 | 26.6.3 | Patch available | GHSA-rr5q-3xwr-f323 |
| — | org.keycloak:keycloak-services (Maven) | before 26.6.3 | 26.6.3 | Patch available | GHSA-rr5q-3xwr-f323 |
- Red Hat build of Keycloak 26.4 VendorRed Hat Affected — Fixed in 26.4.13-1 Patch available CNA
- Red Hat build of Keycloak 26.4 VendorRed Hat Affected — Fixed in 26.4-19 Patch available CNA
- Red Hat build of Keycloak 26.4 VendorRed Hat Affected — Fixed in 26.4-19 Patch available CNA
- Red Hat build of Keycloak 26.4.13 VendorRed Hat Affected — Fixed in — Not affected CNA
- Red Hat build of Keycloak 26.6 VendorRed Hat Affected — Fixed in 26.6.3-3 Patch available CNA
- Red Hat build of Keycloak 26.6 VendorRed Hat Affected — Fixed in 26.6-6 Patch available CNA
- Red Hat build of Keycloak 26.6 VendorRed Hat Affected — Fixed in 26.6-6 Patch available CNA
- Red Hat build of Keycloak 26.6.3 VendorRed Hat Affected — Fixed in — Not affected CNA
- org.keycloak:keycloak-server-spi-private (Maven) Vendor— Affected before 26.6.3 Fixed in 26.6.3 Patch available GHSA-rr5q-3xwr-f323
- org.keycloak:keycloak-services (Maven) Vendor— Affected before 26.6.3 Fixed in 26.6.3 Patch available GHSA-rr5q-3xwr-f323
Remediation
- Fix · GHSA-rr5q-3xwr-f323 org.keycloak:keycloak-server-spi-private (Maven) Fixed in 26.6.3 Advisory →
- Fix · GHSA-rr5q-3xwr-f323 org.keycloak:keycloak-services (Maven) Fixed in 26.6.3 Advisory →
Red Hat 4 advisories
- RHSA-2026:30050 Released 2026-06-25 · Red Hat rating ImportantRed Hat build of Keycloak 26.4.13 Images Security Update
- Red Hat build of Keycloak 26.4 rhbk/keycloak-operator-bundle, rhbk/keycloak-rhel9, rhbk/keycloak-rhel9-operator
- RHSA-2026:30049 Released 2026-06-25 · Red Hat rating ImportantRed Hat build of Keycloak 26.4.13 Security Update
- Red Hat build of Keycloak 26.4.13
- RHSA-2026:25098 Released 2026-06-10 · Red Hat rating ModerateRed Hat build of Keycloak 26.6.3 Update
- Red Hat build of Keycloak 26.6.3
Show 1 more Red Hat advisories
- RHSA-2026:25097 Released 2026-06-10 · Red Hat rating ModerateRed Hat build of Keycloak 26.6.3 Images Update
- Red Hat build of Keycloak 26.6 rhbk/keycloak-operator-bundle, rhbk/keycloak-rhel9, rhbk/keycloak-rhel9-operator
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat build of Keycloak 26.4 | Fixed | RHSA-2026:30050 |
| Red Hat build of Keycloak 26.4.13 | Fixed | RHSA-2026:30049 |
| Red Hat build of Keycloak 26.6 | Fixed | RHSA-2026:25097 |
| Red Hat build of Keycloak 26.6.3 | Fixed | RHSA-2026:25098 |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-9704
- 2026-10-03 Alias added: GHSA-rr5q-3xwr-f323
References
Advisory 7
More Red Hat Build Of Keycloak vulnerabilities
- TI-2026-02223 Keycloak: keycloak: unauthorized authentication via disabled saml identity provider CVSS 3.1HIGH 8.1
- TI-2024-01049 Keycloak: path transversal in redirection validation CVSS 3.1HIGH 8.1
- TI-2026-13740 Keycloak-services: keycloak-services: saml idp-initiated broker login bypasses link-only restriction CVSS 3.1CRITICAL 9.8
- TI-2026-13741 Keycloak-services: keycloak-services: saml broker metadata import disables response signature validation CVSS 3.1CRITICAL 9.1
- TI-2026-13106 Keycloak-services: keycloak-services: dcr protocol mapper type-swap policy bypass allows privilege escalation CVSS 3.1HIGH 8.8
- TI-2026-02631 Authentication bypass in Red Hat build of Keycloak 26.2 CVSS 3.1HIGH 8.8
Sources
- CVE-2026-9704 · CVE Program
- CVE-2026-9704 · NVD
- FIRST EPSS
- GHSA-rr5q-3xwr-f323 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-9704 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences