Keycloak: keycloak: privilege escalation due to oversized subject_token jwt (Red Hat Red Hat build of Keycloak 26.4)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.32 % · percentile 25 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- redhat
- NVD status
- Modified
Description
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.
Weaknesses (CWE)
- CWE-1284 — Improper Validation of Specified Quantity in Input
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | MEDIUM 6.8 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N | redhat |
| CVSS 3.1 | MEDIUM 6.8 | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N | NVD · secalert@redhat.com (Secondary) |
| CVSS 3.1 | HIGH 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | NVD · nvd@nist.gov (Primary) |
Advisories
- GHSA-rr5q-3xwr-f323 — Keycloak Vulnerable to Improper Validation of Specified Quantity in Input
European references
- ENISA EUVD · EUVD-2026-32300
- GCVE · GCVE-0-2026-9704
Affected configurations (NVD CPE)
cpe:2.3:a:redhat:build_of_keycloak:-:*:*:*:-:*:*:*
Affected products
| Product | Versions |
|---|---|
| Red Hat · Red Hat build of Keycloak 26.4 | unaffected 26.4.13-1 < * |
| Red Hat · Red Hat build of Keycloak 26.4 | unaffected 26.4-19 < * |
| Red Hat · Red Hat build of Keycloak 26.4 | unaffected 26.4-19 < * |
| Red Hat · Red Hat build of Keycloak 26.4.13 | |
| Red Hat · Red Hat build of Keycloak 26.6 | unaffected 26.6.3-3 < * |
| Red Hat · Red Hat build of Keycloak 26.6 | unaffected 26.6-6 < * |
| Red Hat · Red Hat build of Keycloak 26.6 | unaffected 26.6-6 < * |
| Red Hat · Red Hat build of Keycloak 26.6.3 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |