CVE-2026-97174
Medium
Description
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.
SeverityMedium
CVSS6.8
Exploit probability—
Product
Red Hat Build of Keycloak
PublishedNov 5, 2026
First seenNov 5, 2026
Weakness typeCWE-20Improper input validation
How to fix
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Red Hat Red Hat Build of Keycloak | No range specified | — |
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