What’s Vulnerable › Vulnerabilities

CVE-2026-97846: Keycloak-services: keycloak-services: standard token exchange v2 bypasses mtls holder-of-key binding

• Severity: medium (CVSS 6.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-25 · updated 2026-09-25
• Weakness: CWE-287

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.

Affected products

• Red Hat build of Keycloak 26.4: all versions

References

• https://access.redhat.com/security/cve/CVE-2026-97846
• https://bugzilla.redhat.com/show_bug.cgi?id=2540949

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