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Vulnerability · Published Jan 21, 2026 · Assigned by redhat

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

Low 3.1

In plain English

A low-severity security flaw in Red Hat build of Keycloak 26.4 from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities).

Severity (CVSS 3.1)3.1Low
Exploit odds (30 days)0.3%top 76.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Mavenorg.keycloak:keycloak-servicesno fix listedGHSA-m2w5-7xhv-w6fh
Ubuntu:24.04:LTSpython-keycloakno fix listedUBUNTU-CVE-2026-1035
Ubuntu:25.10python-keycloakno fix listedUBUNTU-CVE-2026-1035
Ubuntu:26.10python-keycloakno fix listedUBUNTU-CVE-2026-1035

Affected products (as reported)

VendorProductVersions
Red Hat Red Hat build of Keycloak 26.4 see references
Red Hat Red Hat build of Keycloak 26.4 see references
Red Hat Red Hat build of Keycloak 26.4 see references
Red Hat Red Hat build of Keycloak 26.4.11 see references
Red Hat Red Hat JBoss Enterprise Application Platform 8 see references
Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack see references
Red Hat Red Hat Single Sign-On 7 see references

Weakness: CWE-367 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

References