CVE-2026-1035 Org.keycloak.protocol.oidc: keycloak refresh token reuse bypass via toctou race condition
Attackers can bypass refresh token rotation via a race condition, issuing multiple access tokens from a single refresh token in Keycloak.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-1035?
CVE-2026-1035 is a low-severity vulnerability in Red Hat JBoss Enterprise Application Platform 8, published on 21 Jan 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-367
Which versions are affected by CVE-2026-1035?
2 open source packages ship an affected version, including org.keycloak:keycloak-services.
| Package | Affected | Fixed in |
|---|---|---|
org.keycloak:keycloak-services Maven | All versions to 26.2.5 | None |
org.keycloak:keycloak-services Maven | All versions to 26.2.5 | None |
How do I fix CVE-2026-1035?
Apply the vendor's patch.
Is CVE-2026-1035 being exploited?
There is no known exploitation of CVE-2026-1035 in the wild and no public exploit code.
Sources
Also known as GHSA-m2w5-7xhv-w6fh, MINI-9mhq-rqp9-8prm, UBUNTU-CVE-2026-1035.