CVE-2021-21241 Explained : Impact and Mitigation

Flask-Security-Too package versions prior to 3.4.5 are impacted by a CSRF vulnerability that could expose authentication tokens. Here's what you need to know.

Understanding CVE-2021-21241

This vulnerability affects the Flask-Security-Too package versions, allowing malicious sites to acquire user authentication tokens.

What is CVE-2021-21241?

The CSRF vulnerability in Flask-Security-Too versions < 3.4.5 can disclose users' authentication tokens to unauthorized parties via specific endpoints.

The Impact of CVE-2021-21241

With a CVSS base score of 7.4 (high severity), this vulnerability can compromise user confidentiality by allowing unauthorized access to authentication tokens.

Technical Details of CVE-2021-21241

Flask-Security-Too versions < 3.4.5 are susceptible to CSRF attacks due to the exposure of authentication tokens.

Vulnerability Description

The /login and /change endpoints in affected versions can return authentication tokens in response to a GET request, potentially leading to token exposure.

Affected Systems and Versions

Versions >= 3.3.0 and < 3.4.5 of Flask-Security-Too are impacted by this vulnerability.

Exploitation Mechanism

Unauthorized third-party sites can exploit this vulnerability by making GET requests to the /login and /change endpoints to acquire the authentication token.

Mitigation and Prevention

To address CVE-2021-21241, immediate actions and long-term security practices are recommended.

Immediate Steps to Take

Consider patching to fixed versions (3.4.5 and 4.0.0) or set SECURITY_TOKEN_MAX_AGE to "0" to render the token unusable if not needed.

Long-Term Security Practices

Ensure proper CSRF protection, implement secure token management practices, and regularly update the Flask-Security-Too package to prevent future vulnerabilities.

Patching and Updates

Update to fixed versions (3.4.5 and 4.0.0) to mitigate the CSRF vulnerability in Flask-Security-Too.