CVE-2021-41265
📋 TL;DR
CVE-2021-41265 is an authentication bypass vulnerability in Flask-AppBuilder's REST API that allows attackers to craft malicious requests to gain unauthorized access to protected endpoints. This affects systems using non-database authentication methods and new REST API endpoints. Organizations using Flask-AppBuilder for web applications with REST APIs are at risk.
💻 Affected Systems
- Flask-AppBuilder
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of protected REST API endpoints leading to data theft, unauthorized modifications, or privilege escalation depending on endpoint functionality.
Likely Case
Unauthorized access to sensitive data through REST API endpoints, potentially exposing user information or application data.
If Mitigated
Limited impact if proper network segmentation, API rate limiting, and additional authentication layers are in place.
🎯 Exploit Status
The vulnerability requires crafting specific HTTP requests but doesn't require authentication; exploit details are publicly available in the advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.3.4
Vendor Advisory: https://github.com/dpgaspar/Flask-AppBuilder/security/advisories/GHSA-m3rf-7m4w-r66q
Restart Required: Yes
Instructions:
1. Update Flask-AppBuilder using pip: 'pip install Flask-AppBuilder==3.3.4' or 'pip install --upgrade Flask-AppBuilder'. 2. Restart your Flask application. 3. Verify the update with 'pip show Flask-AppBuilder'.
🔧 Temporary Workarounds
Disable vulnerable REST API endpoints
allTemporarily disable or restrict access to Flask-AppBuilder REST API endpoints until patching is complete.
Modify Flask application configuration to disable REST API or implement additional authentication middleware
Implement Web Application Firewall (WAF) rules
allDeploy WAF rules to block malicious requests targeting Flask-AppBuilder REST API endpoints.
Configure WAF to inspect and block requests with suspicious authentication patterns to /api/* endpoints
🧯 If You Can't Patch
- Implement network-level access controls to restrict access to Flask-AppBuilder REST API endpoints
- Deploy additional authentication layer (API gateway, reverse proxy with auth) in front of vulnerable endpoints
🔍 How to Verify
Check if Vulnerable:
Check Flask-AppBuilder version and authentication configuration. Vulnerable if version < 3.3.4 and using non-database authentication with REST API endpoints.Check Version:
pip show Flask-AppBuilder | grep VersionVerify Fix Applied:
Verify Flask-AppBuilder version is 3.3.4 or higher and test REST API authentication functionality.📡 Detection & Monitoring
Log Indicators:
- Unusual authentication patterns in REST API logs
- Failed authentication attempts followed by successful access to protected endpoints
- Requests to /api/* endpoints with crafted authentication headers
Network Indicators:
- HTTP requests to REST API endpoints with unusual authentication parameters
- Traffic patterns showing authentication bypass attempts
SIEM Query:
source="flask-appbuilder" AND (event_type="authentication" OR endpoint="/api/*") AND (status="success" AND previous_status="failed")🔗 References
- https://github.com/dpgaspar/Flask-AppBuilder/commit/eba517aab121afa3f3f2edb011ec6bc4efd61fbc
- https://github.com/dpgaspar/Flask-AppBuilder/releases/tag/v3.3.4
- https://github.com/dpgaspar/Flask-AppBuilder/security/advisories/GHSA-m3rf-7m4w-r66q
- https://github.com/dpgaspar/Flask-AppBuilder/commit/eba517aab121afa3f3f2edb011ec6bc4efd61fbc
- https://github.com/dpgaspar/Flask-AppBuilder/releases/tag/v3.3.4
- https://github.com/dpgaspar/Flask-AppBuilder/security/advisories/GHSA-m3rf-7m4w-r66q
