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CVE-2026-118030medium4.2

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

Impact

A flaw in Keycloak-services' HOTP authentication allows an attacker with a user's password to reuse a one-time code for multiple concurrent logins due to a race condition. The issue occurs because the system validates and updates the internal counter in separate steps without proper locking. This affects Red Hat Build of Keycloak.

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

What to do

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.

redhat guidance

Affected packages

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Affected products

Vendor version evidence. Product records are separate from automatic dependency matching.

Red Hat · redhat

Red Hat Build of Keycloak

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redhat version evidence

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:build_keycloak:

Red Hat · redhat

Red Hat Build of Keycloak

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affected

unaffected

unknown

Other versions: affected

Product identifiers (CPE)cpe:/a:redhat:build_keycloak:

Red Hat · redhat

Red Hat Single Sign-On 7

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affected

unaffected

unknown

Other versions: unaffected

Product identifiers (CPE)cpe:/a:redhat:red_hat_single_sign_on:7

Original source 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.

Inside the record

Evidence available

Package identity · not supplied
Version evidence · not supplied
Remediation guidance
Weakness classification
Additional publishers

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Original records

CVE-2026-118030

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Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-362 ↗

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

redhat

Related →
Contributing organizations · 2
redhat

Assigning organization

2026-10-29
CISA-ADP

Additional data publisher

2026-10-29

What changed

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References

2 sources
access.redhat.com/security/cve/CVE-2026-118030
vdb-entryredhat
bugzilla.redhat.com/show_bug.cgi
issue-trackingredhat