Observable Response Discrepancy in Flask-AppBuilder
Impact
User enumeration in database authentication in Flask-AppBuilder <= 3.2.3. Allows for a non authenticated user to enumerate existing accounts by timing the response time from the server when you are logging in.
Patches
Upgrade to 3.3.0
For more information
If you have any questions or comments about this advisory:
- Open an issue in Flask-AppBuilder
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | flask-appbuilder | < 3.3.0 | 3.3.0 |
References
- https://github.com/dpgaspar/Flask-AppBuilder/commit/780bd0e8fbf2d36ada52edb769477e0a4edae580
- https://github.com/dpgaspar/Flask-AppBuilder/security/advisories/GHSA-434h-p4gx-jm89
- https://pypi.org/project/Flask-AppBuilder/
- https://nvd.nist.gov/vuln/detail/CVE-2021-29621
- https://github.com/dpgaspar/Flask-AppBuilder
- https://github.com/pypa/advisory-database/tree/main/vulns/flask-appbuilder/PYSEC-2021-90.yaml
- https://lists.apache.org/thread.html/r466759f377651f0a690475d5a52564d0e786e82c08d5a5730a4f8352%40%3Cannounce.apache.org%3E
- https://lists.apache.org/thread.html/r466759f377651f0a690475d5a52564d0e786e82c08d5a5730a4f8352@%3Cannounce.apache.org%3E
- https://lists.apache.org/thread.html/r5b754118ba4e996adf03863705d34168bffec202da5c6bdc9bf3add5%40%3Cannounce.apache.org%3E
- https://lists.apache.org/thread.html/r5b754118ba4e996adf03863705d34168bffec202da5c6bdc9bf3add5@%3Cannounce.apache.org%3E
- https://lists.apache.org/thread.html/r91067f953906d93aaa1c69fe2b5472754019cc6bd4f1ba81349d62a0%40%3Ccommits.airflow.apache.org%3E
- https://lists.apache.org/thread.html/r91067f953906d93aaa1c69fe2b5472754019cc6bd4f1ba81349d62a0@%3Ccommits.airflow.apache.org%3E
- https://pypi.org/project/Flask-AppBuilder
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N- Weakness (CWE)
CWE-203- Platform
- Python (PyPI)
- Package
flask-appbuilder- Disclosed
- 27.05.2021
- Updated
- 11.10.2026 13:19
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2021-90 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-434h-p4gx-jm89 - CC BY 4.0
Vulnerability history: flask-appbuilder
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 14
- First → latest
- 05.2021 09.2025
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 2
- Medium 9
- Low 2
Disclosures per year
- 2021: 3
- 2022: 3
- 2023: 2
- 2024: 3
- 2025: 3
- 2026: 0
-
Observable Response Discrepancy in Flask-AppBuilder this entry
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