CVSS 3.1
8.8 highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HCVE-2026-9704
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.
Severity
- EPSS
- 0.3% chance of exploitation in the next 30 days; higher than 25% of CVEs (scores of 2026-10-31)
- CWE
- CWE-1284
- Published
- Modified
- Record from
- the NVD, synced
Affected
- redhat:build_of_keycloak
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-rr5q-3xwr-f323 | Maven | org.keycloak:keycloak-server-spi-private | <26.6.3 | 26.6.3 |
| GHSA-rr5q-3xwr-f323 | Maven | org.keycloak:keycloak-services | <26.6.3 | 26.6.3 |