CVE-2026-97846
Description
Keycloak provides a feature called mTLS holder-of-key binding which ensures that a token can only be used by the client that originally requested it by binding it to their digital certificate. A flaw was discovered where the new Standard Token Exchange V2 feature does not check for this certificate. This allows an attacker with stolen client credentials to obtain a standard, unrestricted token that bypasses these security protections.
Statement
The Red Hat Product Security team has assessed the severity of this vulnerability as Moderate, given that exploitation requires the attacker to already possess valid client credentials and a valid subject token, and requires specific non-default configurations. Successful exploitation allows an attacker to bypass mTLS sender-constraints and obtain unconstrained Bearer tokens. The vulnerability's root cause is a missing enforcement check for client certificates in the Standard Token Exchange V2 grant provider.
Mitigation
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
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 | 6.8 | N/A | 6.8 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | Low | N/A | Low |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability,Access Control
Technical Impact: Read Application Data; Gain Privileges or Assume Identity; Execute Unauthorized Code or Commands
This weakness can lead to the exposure of resources or functionality to unintended actors, possibly providing attackers with sensitive information or even execute arbitrary code.
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