CVE-2026-16089
Description
A flaw was found in the keycloak-services component of Red Hat Build of Keycloak. The issue occurs because OAuth 2.0 authorization codes are not properly bound to the client that originally requested them. An attacker who can intercept an authorization code can modify it to be redeemed by their own client, potentially allowing them to obtain access tokens for a victim's identity.
Statement
The Red Hat Product Security team has assessed the severity of this vulnerability as Moderate, given that exploitation requires the attacker to intercept a valid authorization code and have a registered client in the same realm. Successful exploitation allows an attacker to retarget an authorization code to their own client and obtain tokens for the victim's identity. The vulnerability's root cause is the lack of binding between the authorization code and the issuing client identifier in the code payload.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.4 | 5.9 | 5.4 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | High | High |
| Privileges Required | Low | None | Low |
| User Interaction | Required | Required | Required |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | Low | Low | Low |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N
NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:N
Acknowledgements
Red Hat would like to thank Paul Bottinelli (Trail of Bits) for reporting this issue.
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