Account linking via unbound OAuth state
Published Dec 19, 2025 · Updated Dec 19, 2025
Cross-site request forgery in FastAPI SSO before 0.19.0 allows remote authenticated users to link an SSO identity to a victim account. The get_login_url method does not persist state for the initiating session, and verify_and_process accepts the callback state without comparing it with a trusted local value. Exploitation requires victim interaction and application logic that links a callback identity to an authenticated internal account, enabling permanent takeover.
Summary
What happened
Cross-site request forgery in FastAPI SSO before 0.19.0 allows remote authenticated users to link an SSO identity to a victim account. The get_login_url method does not persist state for the initiating session, and verify_and_process accepts the callback state without comparing it with a trusted local value. Exploitation requires victim interaction and application logic that links a callback identity to an authenticated internal account, enabling permanent takeover.
The record
- CVE
- CVE-2025-14546
- Published
- Dec 19, 2025
- Updated
- Dec 19, 2025
- Vendor
- Tomas Votava
- Product
- FastAPI SSO
- Classifications
- CWE-285, T1566.002
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Dec 19, 2025CVE publishedPublication date reported by the CVE source.
- Dec 19, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <0.19.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- OAuth callback account-linking proof of conceptproof of concept · unverified
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Technologies
Your stack
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Your stack
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