CVE-2026-118030

Keycloak-services: keycloak-services: hotp race condition allows single otp code reuse across concurrent logins

Published Oct 29, 2026 CVSS 3.1 · 4.2 Medium EPSS < 1% KEV · Not listed
Description
A flaw was found in the HOTP authentication mechanism of the keycloak-services component, which provides identity and access management services. The issue occurs because the system validates a one-time password and updates its internal counter in two separate steps without proper locking. An attacker with a users password could exploit this timing gap to use a single one-time code to log in multiple times simultaneously.

Remediation

Vendor Workaround

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Red Hat
Red Hat red Hat Build Of Keycloak 26.4
Redhat build Of Keycloak
Redhat single Sign-on
Vendors & Products Red Hat
Red Hat red Hat Build Of Keycloak 26.4
Redhat build Of Keycloak
Redhat single Sign-on
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A flaw was found in the HOTP authentication mechanism of the keycloak-services component, which provides identity and access management services. The issue occurs because the system validates a one-time password and updates its internal counter in two separate steps without proper locking. An attacker with a users password could exploit this timing gap to use a single one-time code to log in multiple times simultaneously.
Title Keycloak-services: keycloak-services: hotp race condition allows single otp code reuse across concurrent logins
First Time appeared Redhat
Redhat build Keycloak
Redhat red Hat Single Sign On
Weaknesses CWE-362
CPEs cpe:/a:redhat:build_keycloak:
cpe:/a:redhat:red_hat_single_sign_on:7
Vendors & Products Redhat
Redhat build Keycloak
Redhat red Hat Single Sign On
References
Metrics cvssV3_1

{'score': 4.2, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Nov 6, 2026, 6:24 AM
Reserved
Oct 27, 2026, 2:17 PM
Status
Awaiting Analysis
Published
Oct 29, 2026, 7:16 AM
Modified
Oct 29, 2026, 3:17 PM
Severity
Moderate
Public date
Oct 26, 2026, 1:54 PM