Username enumeration via unbalanced login hashing
Published Jun 7, 2021 · Updated Aug 3, 2024
Timing discrepancy in Flask-AppBuilder before 3.3.0 allows remote attackers to enumerate database-authentication usernames. In auth_user_db, nonexistent or inactive users return without password-hash verification, while existing users incur a PBKDF2 check, exposing account existence through response time. Database authentication must be enabled and the login route reachable; the result discloses valid account names but does not grant account access.
Summary
What happened
Timing discrepancy in Flask-AppBuilder before 3.3.0 allows remote attackers to enumerate database-authentication usernames. In auth_user_db, nonexistent or inactive users return without password-hash verification, while existing users incur a PBKDF2 check, exposing account existence through response time. Database authentication must be enabled and the login route reachable; the result discloses valid account names but does not grant account access.
The record
- CVE
- CVE-2021-29621
- Published
- Jun 7, 2021
- Updated
- Aug 3, 2024
- Vendor
- dpgaspar
- Product
- Flask-AppBuilder
- Classifications
- CWE-203, CAPEC-189, T1087
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 7, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 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?
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- Affected versionversion=< 3.3.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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