CVE-2026-9704Keycloak: keycloak: privilege escalation due to oversized subject_token jwt
Updated under an hour ago ()
This data is behind schedule: last updated Oct 26, 2026, 6:40 AM ET. We are working on it.Behind: CVE records (cvelistV5).
Does this affect you?
It affects Red Hat build of Keycloak 26.4 and 1 other product. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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Free account, 1 product
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.
- CVSS
- 6.8 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
- Weakness (CWE)
- CWE-1284
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- redhat
- NVD analysis
- Modified
- Record last updated
- Jun 26, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Red Hat Red Hat build of Keycloak 26.4 redhat:build_keycloak | from 26.4.13-1 not affected | CNA record |
redhat build_of_keycloak redhat:build_of_keycloak | all versions | NVD |
References
- https://access.redhat.com/errata/RHSA-2026:25097vendor-advisory, x-refsource-redhat
- https://access.redhat.com/errata/RHSA-2026:25098vendor-advisory, x-refsource-redhat
- https://access.redhat.com/errata/RHSA-2026:30049vendor-advisory, x-refsource-redhat
- https://access.redhat.com/errata/RHSA-2026:30050vendor-advisory, x-refsource-redhat
- https://access.redhat.com/security/cve/CVE-2026-9704vdb-entry, x-refsource-redhat, mitigation, vendor-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2481877issue-tracking, x-refsource-redhat, vendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.