Vulnerability in Red Hat Build Of Keycloak 26.4
CVE-2026-1035
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.
Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.1 (Low). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N.
EPSS exploit prediction
EPSS: 0.003 (21.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 21st percentile — 21.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000
Affected products
Weakness classification (CWE)
References
- access.redhat.com/errata/RHSA-2026:6477 (vendor-advisory)
- access.redhat.com/errata/RHSA-2026:6478 (vendor-advisory)
- access.redhat.com/security/cve/CVE-2026-1035 (vdb-entry)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking)
Frequently asked questions
- What is CVE-2026-1035?
- CVE-2026-1035 is a low-severity vulnerability in Red Hat Build Of Keycloak 26.4, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 3.1/10. Published 2026-01-21.
- How severe is CVE-2026-1035?
- Low severity. CVSS v3 base score is 3.1 out of 10.