CVE-2026-97174
Keycloak-services: keycloak-services: ciba sub parameter injection causes attacker authentication to issue victim tokens
A flaw was found in the Client-Initiated Backchannel Authentication (CIBA) implementation of Keycloak. The CIBA endpoint fails to properly validate the sub parameter, allowing it to be stored as an additional request parameter. During the token issuance process, this injected value overwrites the legitimate subject identifier. This allows an attacker to authenticate as themselves but receive security tokens belonging to a different victim user, leading to unauthorized account access.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- High
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Keycloak-services: keycloak-services: ciba sub parameter injection causes attacker authentication to issue victim tokens
A flaw was found in the Client-Initiated Backchannel Authentication (CIBA) implementation of Keycloak. The CIBA endpoint fails to properly validate the sub parameter, allowing it to be stored as an additional request parameter. During the token issuance process, this injected value overwrites the legitimate subject identifier. This allows an attacker to authenticate as themselves but receive security tokens belonging to a different victim user, leading to unauthorized account access.
- Record
CVE-2026-97174- CVSS 3.1
- 6.8 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-20
- Updated
- 2026-11-06
EUVDEUVD-2026-117610
A flaw was found in the Client-Initiated Backchannel Authentication (CIBA) implementation of Keycloak. The CIBA endpoint fails to properly validate the sub parameter, allowing it to be stored as an additional request parameter. During the token issuance process, this injected value overwrites the legitimate subject identifier. This allows an attacker to authenticate as themselves but receive security tokens belonging to a different victim user, leading to unauthorized account access.
- Record
EUVD-2026-117610- CVSS 3.1
- 6.8 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N - Updated
- 2026-11-06
GitHub AdvisoriesGHSA-42wm-mqj8-5cwr
A flaw was found in the Client-Initiated Backchannel Authentication (CIBA) implementation of...
A flaw was found in the Client-Initiated Backchannel Authentication (CIBA) implementation of Keycloak. The CIBA endpoint fails to properly validate the sub parameter, allowing it to be stored as an additional request parameter. During the token issuance process, this injected value overwrites the legitimate subject identifier. This allows an attacker to authenticate as themselves but receive security tokens belonging to a different victim user, leading to unauthorized account access.
- Record
GHSA-42wm-mqj8-5cwr- CVSS 3.1
- 6.8 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-20
- Updated
- 2026-11-06
NVD
A flaw was found in the Client-Initiated Backchannel Authentication (CIBA) implementation of Keycloak. The CIBA endpoint fails to properly validate the sub parameter, allowing it to be stored as an additional request parameter. During the token issuance process, this injected value overwrites the legitimate subject identifier. This allows an attacker to authenticate as themselves but receive security tokens belonging to a different victim user, leading to unauthorized account access.
- Record
CVE-2026-97174- CVSS 3.1
- 6.8 Medium
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N - Weakness
- CWE-20
- Updated
- 2026-11-06
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| references | CVE List | |
| products, references | EUVD, GitHub Advisories, NVD | |
| products, references | CVE List | |
| references | CVE List, EUVD, NVD | |
| aliases, references | GitHub Advisories | |
| cwes, products, references, severity, title | CVE List | |
| first indexed | EUVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-97174 is a medium vulnerability (CVSS 6.8) in Red Hat Build Of Keycloak 26.6, published November 5, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.37%, the 30th percentile. No source names a fixed version.