CVE-2024-39912

Enumeration of valid usernames in web-auth/webauthn-lib

Published Jul 15, 2024 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
web-auth/webauthn-lib is an open source set of PHP libraries and a Symfony bundle to allow developers to integrate that authentication mechanism into their web applications. The ProfileBasedRequestOptionsBuilder method returns allowedCredentials without any credentials if no username was found. When WebAuthn is used as the first or only authentication method, an attacker can enumerate usernames based on the absence of the `allowedCredentials` property in the assertion options response. This allows enumeration of valid or invalid usernames. By knowing which usernames are valid, attackers can focus their efforts on a smaller set of potential targets, increasing the efficiency and likelihood of successful attacks. This issue has been addressed in version 4.9.0 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

Remediation

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Advisories

Source ID Title
EUVD EUVD EUVD-2024-2291 web-auth/webauthn-lib is an open source set of PHP libraries and a Symfony bundle to allow developers to integrate that authentication mechanism into their web applications. The ProfileBasedRequestOptionsBuilder method returns allowedCredentials without any credentials if no username was found. When WebAuthn is used as the first or only authentication method, an attacker can enumerate usernames based on the absence of the `allowedCredentials` property in the assertion options response. This allows enumeration of valid or invalid usernames. By knowing which usernames are valid, attackers can focus their efforts on a smaller set of potential targets, increasing the efficiency and likelihood of successful attacks. This issue has been addressed in version 4.9.0 and all users are advised to upgrade. There are no known workarounds for this vulnerability.
Github GHSA Github GHSA GHSA-875x-g8p7-5w27 The FIDO2/Webauthn Support for PHP library allows enumeration of valid usernames
History

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Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Aug 2, 2024, 4:33 AM
Reserved
Jul 2, 2024, 7:37 PM
Status
Deferred
Published
Jul 15, 2024, 8:15 PM
Modified
Jun 17, 2026, 7:43 AM