CVE-2026-1035
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.
Statement
This vulnerability is rated LOW for Red Hat. A race condition in the Keycloak TokenManager allows an attacker to bypass the refreshTokenMaxReuse security policy when it is explicitly configured for strict single-use (set to zero). This enables a single refresh token to be exchanged for multiple valid access tokens through concurrent requests, undermining the Refresh Token Rotation hardening measure.
Mitigation
To mitigate this issue, configure the `refreshTokenMaxReuse` policy in Keycloak to a value greater than zero. This prevents the race condition by allowing a limited number of reuses for refresh tokens, thereby maintaining the integrity of the Refresh Token Rotation hardening measure. Consult Keycloak documentation for specific configuration instructions. Changes to Keycloak configuration typically require a service restart or redeployment to take effect.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 3.1 | N/A | 3.1 |
| 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 | None | N/A | None |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
Acknowledgements
Red Hat would like to thank Mohamed Amine ait Ouchebou (mrecho) (Indiesecurity) for reporting this issue.
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