How severe is CVE-2024-39912?

CVE-2024-39912 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2024-39912 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2024-39912?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2024-39912 have an EU (EUVD) identifier?

Yes. CVE-2024-39912 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-2291.

When was CVE-2024-39912 published?

CVE-2024-39912 was published on 2024-07-15 and last updated on 2026-06-17.

CVE-2024-39912

CVE-2024-39912 is a medium-severity vulnerability with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-204.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 0% (31st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2024-2291
Weakness: CWE-204
Published: 2024-07-15
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2024-39912?: 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.
How severe is CVE-2024-39912?: CVE-2024-39912 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2024-39912 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (31st percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2024-39912?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2024-39912 have an EU (EUVD) identifier?: Yes. CVE-2024-39912 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-2291.
When was CVE-2024-39912 published?: CVE-2024-39912 was published on 2024-07-15 and last updated on 2026-06-17.

References

Other CWE-204 vulnerabilities

CVE-2018-25350 — Critical (CVSS 9.8): userSpice 4.3.24 contains a username enumeration vulnerability that allows unauthenticated attackers to discover valid…
CVE-2025-5485 — High (CVSS 8.6): User names used to access the web management interface are limited to the device identifier, which is a numerical…
CVE-2026-33419 — High (CVSS 7.5): MinIO is a high-performance object storage system. Prior to RELEASE.2026-03-17T21-25-16Z, MinIO AIStor's STS (Security…
CVE-2025-12455 — High (CVSS 7.5): Observable response discrepancy vulnerability in OpenText™ Vertica allows Password Brute Forcing. The…
CVE-2025-46390 — High (CVSS 7.5): CWE-204: Observable Response Discrepancy
CVE-2025-3092 — High (CVSS 7.5): An unauthenticated remote attacker can enumerate valid user names from an unprotected endpoint.

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