What’s Vulnerable › Vulnerabilities

CVE-2026-1035: Org.keycloak.protocol.oidc: keycloak refresh token reuse bypass via toctou race condition

• Severity: low (CVSS 3.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-01-21 · updated 2026-06-17
• Weakness: CWE-367

Description

A flaw was found in the Keycloak server during refresh token processing, specifically in the TokenManager class responsible for enforcing refresh token reuse policies. When strict refresh token rotation is enabled, the validation and update of refresh token usage are not performed atomically. This allows concurrent refresh requests to bypass single-use enforcement and issue multiple access tokens from the same refresh token. As a result, Keycloak’s refresh token rotation hardening can be undermined.

Affected products

• Red Hat build of Keycloak 26.4: all versions — fixed in 26.4-14, 26.4.11-1

How to fix

Upgrade to a fixed version: Red Hat build of Keycloak 26.4 26.4-14, 26.4.11-1. Check the vendor advisory for mitigations.

References

• https://access.redhat.com/errata/RHSA-2026:6477
• https://access.redhat.com/errata/RHSA-2026:6478
• https://access.redhat.com/security/cve/CVE-2026-1035
• https://bugzilla.redhat.com/show_bug.cgi?id=2430314

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