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Fencer Vulns
low 3.1

CVE-2026-1035 json

Org.keycloak.protocol.oidc: keycloak refresh token reuse bypass via toctou race condition

published 2026-01-21 9 mo ago modified 2026-06-17 4 mo ago also GHSA-m2w5-7xhv-w6fh , EUVD-2026-3691

cvss
3.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 23%
public exploits
0
none known

Summary

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.

Patch / fix

  • Red Hat Red Hat build of Keycloak 26.4 26.4-14, 26.4.11-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-1035 updated cvss 3.1

org.keycloak.protocol.oidc: Keycloak Refresh Token Reuse Bypass via TOCTOU Race Condition

  • Red Hat build of Keycloak 26.4 rhbk/keycloak-rhel9 26.4-14, rhbk/keycloak-rhel9-operator 26.4-14, rhbk/keycloak-operator-bundle 26.4.11-1
    fixed: vendor fix RHSA-2026:6478
  • Red Hat build of Keycloak 26.4.11
    fixed: vendor fix RHSA-2026:6477
  • Red Hat JBoss Enterprise Application Platform 8 keycloak-services Red Hat JBoss Enterprise Application Platform Expansion Pack keycloak-services Red Hat Single Sign-On 7 keycloak-services
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
9 mo ago

Exploit prediction

0.30% chance of exploitation in the next 30 days, higher than 23% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
GitHub 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
maven org.keycloak:keycloak-services
<=26.2.5
 no fix listed

Affected products

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

Classification

Weakness
  • CWE-367 Time-of-check Time-of-use (TOCTOU) Race Condition

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.