Multiple access-token issuance via non-atomic reuse validation
Published Jan 21, 2026 · Updated Jan 21, 2026
Race condition in Red Hat build of Keycloak 26.4 allows remote authenticated users to mint multiple access tokens from one refresh token. TokenManager.validateTokenReuse checks the refresh-token reuse counter separately from updating it, so concurrent refresh requests pass before the counter changes. Exploitation requires a valid refresh token and refreshTokenMaxReuse set to zero; the resulting tokens retain that user session's existing privileges.
Summary
What happened
Race condition in Red Hat build of Keycloak 26.4 allows remote authenticated users to mint multiple access tokens from one refresh token. TokenManager.validateTokenReuse checks the refresh-token reuse counter separately from updating it, so concurrent refresh requests pass before the counter changes. Exploitation requires a valid refresh token and refreshTokenMaxReuse set to zero; the resulting tokens retain that user session's existing privileges.
The record
- CVE
- CVE-2026-1035
- Published
- Jan 21, 2026
- Updated
- Jan 21, 2026
- Vendor
- 389 Directory Server
- Product
- Red Hat build of Keycloak
- Classifications
- CWE-367, T1550.001
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jan 21, 2026CVE publishedPublication date reported by the CVE source.
- Jan 21, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Technologies
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Your stack
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