Observable Response Discrepancy in Flask-AppBuilder
Priority LOW 30CWE-203Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- Low · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-203.
Summary
Flask-AppBuilder is a development framework, built on top of Flask. 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. Upgrade to version 3.3.0 or higher to resolve.
Why it matters now
EPSS 0.03404 88th percentileScored 2026-11-07
Fix Fixed Flask-AppBuilder (dpgaspar): 3.3.0Flask-AppBuilder (PyPI): 3.3.0
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| dpgaspar | Flask-AppBuilder | before 3.3.0 | 3.3.0 | Patch available | CNA |
| — | Flask-AppBuilder (PyPI) | before 3.3.0 | 3.3.0 | Patch available | GHSA-434h-p4gx-jm89 |
- Flask-AppBuilder Vendordpgaspar Affected before 3.3.0 Fixed in 3.3.0 Patch available CNA
- Flask-AppBuilder (PyPI) Vendor— Affected before 3.3.0 Fixed in 3.3.0 Patch available GHSA-434h-p4gx-jm89
Remediation
- Fix · CNA Flask-AppBuilder (dpgaspar) Fixed in 3.3.0
- Fix · GHSA-434h-p4gx-jm89 Flask-AppBuilder (PyPI) Fixed in 3.3.0 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2021-29621
- 2026-10-03 Alias added: GHSA-434h-p4gx-jm89
References
Advisory 3
Other 9
- [announce] 20210618 Apache Airflow CVE: CVE-2021-29621: User enumeration in database authentication in Flask-AppBuilder <= 3.2.3.
- [announce] 20210623 Success at Apache: Security in Practice
- [airflow-commits] 20210712 [GitHub] [airflow] ashb commented on pull request #16942: Relax version constraint on ``Flask-Appbuilder``
- 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@%3Cannounce.apache.org%3E
- https://lists.apache.org/thread.html/r5b754118ba4e996adf03863705d34168bffec202da5c6bdc9bf3add5@%3Cannounce.apache.org%3E
- https://lists.apache.org/thread.html/r91067f953906d93aaa1c69fe2b5472754019cc6bd4f1ba81349d62a0@%3Ccommits.airflow.apache.org%3E
- https://pypi.org/project/Flask-AppBuilder
More dpgaspar Flask-appbuilder vulnerabilities
- TI-2024-17946 Flask-AppBuilder's OAuth login page subject to Cross Site Scripting (XSS) CVSS 3.1MEDIUM 6.1
- TI-2024-16581 Flask-AppBuilder incorrect authentication when using auth type OpenID CVSS 3.1CRITICAL 9.1
- TI-2021-18097 Improper Authentication in Flask-AppBuilder CVSS 3.1HIGH 8.8
- TI-2023-13466 No Rate Limiting on Login AUTH DB CVSS 3.1HIGH 7.5
- TI-2021-12470 URL Redirection to Untrusted Site ('Open Redirect') in Flask-AppBuilder CVSS 3.1HIGH 7.2
- TI-2022-06037 Observable Response Discrepancy in Flask-AppBuilder CVSS 3.1MEDIUM 5.3
Sources
- CVE-2021-29621 · CVE Program
- CVE-2021-29621 · NVD
- FIRST EPSS
- GHSA-434h-p4gx-jm89 · GitHub Advisory Database · CC BY 4.0
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