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.
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.
왜 이 VPI인가 (설명가능 · 실험적)
VPI 산정 기준
| 영향도 | 68.00 |
| 악용 신호(추가 악용신호 없음) | ×1.00 |
| VPI | 68.00 |
VPI 공식 vpi-v1 기준
| 소스 | CVSS 버전 | 기본 점수 | 심각도 | 벡터 문자열 | 평가일 |
|---|---|---|---|---|---|
| OSV3rd | 3.1 | 6.8 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N | 2026. 07. 02. |
| NVDNIST | 3.1 | 6.8 |
| CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N |
| 2026. 05. 27. |