FastAPI SSP is vulnerable to Cross-site Request Forgery (CSRF) through improper OAuth parameter validation
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.
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | fastapi-sso | < 0.19.0 | 0.19.0 |
References
- https://nvd.nist.gov/vuln/detail/CVE-2025-14546
- https://github.com/tomasvotava/fastapi-sso/issues/266
- https://github.com/tomasvotava/fastapi-sso/commit/6117d1a5ad498ba57d671e8a059ebe20db5abe02
- https://github.com/tomasvotava/fastapi-sso
- https://security.snyk.io/vuln/SNYK-PYTHON-FASTAPISSO-14386403
- https://pypi.org/project/fastapi-sso
- https://github.com/advisories/GHSA-hp6r-r9vc-q8wx
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N- Weakness (CWE)
CWE-285- Platform
- Python (PyPI)
- Package
fastapi-sso- Disclosed
- 19.12.2025
- Updated
- 11.10.2026 15:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-1362 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-hp6r-r9vc-q8wx - CC BY 4.0
Vulnerability history: fastapi-sso
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.