CVE-2026-118030: Keycloak-services: keycloak-services: hotp race condition allows single otp code reuse across concurrent logins

Severity: medium (CVSS 4.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-29 · updated 2026-10-29
Weakness: CWE-362

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

Red Hat build of Keycloak 26.4: all versions

References

https://access.redhat.com/security/cve/CVE-2026-118030
https://bugzilla.redhat.com/show_bug.cgi?id=2562005

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