Username enumeration via missing allowedCredentials response
Published Jul 15, 2024 · Updated Aug 2, 2024
Observable response discrepancy in Webauthn Framework 4.5.0 and later, before 4.9.0, allows remote attackers to enumerate valid usernames. ProfileBasedRequestOptionsBuilder omits allowedCredentials when lookup finds no username but returns account-linked descriptors for existing users. The exposure requires WebAuthn as the first or only authentication method and discloses only whether submitted usernames are registered.
Summary
What happened
Observable response discrepancy in Webauthn Framework 4.5.0 and later, before 4.9.0, allows remote attackers to enumerate valid usernames. ProfileBasedRequestOptionsBuilder omits allowedCredentials when lookup finds no username but returns account-linked descriptors for existing users. The exposure requires WebAuthn as the first or only authentication method and discloses only whether submitted usernames are registered.
The record
- CVE
- CVE-2024-39912
- Published
- Jul 15, 2024
- Updated
- Aug 2, 2024
- Vendor
- Web-Authentication
- Product
- Webauthn Framework
- Classifications
- CWE-204, T1589.001
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 15, 2024CVE publishedPublication date reported by the CVE source.
- Aug 2, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 4.5.0, < 4.9.0
- Affected versionversion=4.5.0 <4.9.0
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Assertion-options username enumeration proof of conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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