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Medium · 4.2 CVE-2026-118030 EUVD-2026-112640GHSA-hx7p-ffjf-vx59

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

Published Oct 29, 2026 · Updated Nov 6, 2026 · Assigned by redhat

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.

Affected products

VendorProductAffectedFixed
Red Hat Red Hat Build of Keycloak — —
Red Hat Red Hat Single Sign-On 7 — —

Advisories 1

References