fastapi-sso up to 0.18.x get_login_url cross-site request forgery

Summaryinfo

A vulnerability described as problematic has been identified in fastapi-sso up to 0.18.x. The affected element is the function get_login_url. Executing a manipulation can lead to cross-site request forgery. This vulnerability is tracked as CVE-2025-14546. The attack can be launched remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in fastapi-sso up to 0.18.x. It has been declared as problematic. This vulnerability affects the function get_login_url. The manipulation with an unknown input leads to a cross-site request forgery vulnerability. The CWE definition for the vulnerability is CWE-352. The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request. As an impact it is known to affect integrity. CVE summarizes:

Versions of the package fastapi-sso before 0.19.0 are vulnerable to Cross-site Request Forgery (CSRF) due to the improper validation of the OAuth state parameter during the authentication callback. While the get_login_url method allows for state generation, it does not persist the state or bind it to the user's session. Consequently, the verify_and_process method accepts the state received in the query parameters without verifying it against a trusted local value. This allows a remote attacker to trick a victim into visiting a malicious callback URL, which can result in the attacker's account being linked to the victim's internal account.

The advisory is shared for download at security.snyk.io. This vulnerability was named CVE-2025-14546 since 12/11/2025. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available.

Upgrading to version 0.19.0 eliminates this vulnerability. Applying the patch 6117d1a5ad498ba57d671e8a059ebe20db5abe02 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-204438). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

• fastapi-sso

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7
• 0.8
• 0.9
• 0.10
• 0.11
• 0.12
• 0.13
• 0.14
• 0.15
• 0.16
• 0.17
• 0.18

License

• open-source

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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