Vulnerability · Published Oct 29, 2026 · Assigned by redhat

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

Medium 4.2

In plain English

A medium-severity race condition in Red Hat Build of Keycloak from Red Hat. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 6% of all known vulnerabilities).

Severity (CVSS 3.1)4.2Medium

Exploit odds (30 days)0.2%top 94.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official 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 (as reported)

Vendor	Product	Versions
Red Hat	Red Hat Build of Keycloak	see references
Red Hat	Red Hat Build of Keycloak	see references
Red Hat	Red Hat Single Sign-On 7	see references

Weakness: CWE-362 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:N

References

https://access.redhat.com/security/cve/CVE-2026-118030 vdb-entry, x_refsource_REDHAT
RHBZ#2562005 issue-tracking, x_refsource_REDHAT