CVE-2025-14546
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- Active
What an attacker can affect
- Confidentiality
- High
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
6.9
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.
- Record
CVE-2025-14546- CVSS 4.0
- 6.9 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:P - CVSS 3.1
- 6.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N/E:P - Weakness
- CWE-285
- Updated
- 2026-11-02
EUVDEUVD-2025-204438
6.9
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.
- Record
EUVD-2025-204438- CVSS 4.0
- 6.9 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:P - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-hp6r-r9vc-q8wx
5.4
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.
- Record
GHSA-hp6r-r9vc-q8wx- CVSS 4.0
- 5.4 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:P - CVSS 3.1
- 6.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N - Weakness
- CWE-285
- Updated
- 2026-11-02
NVD
5.4
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.
- Record
CVE-2025-14546- CVSS 4.0
- 5.4 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 6.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N - Weakness
- CWE-285
- Updated
- 2026-11-02
OSV
5.4
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.
- Record
CVE-2025-14546- CVSS 4.0
- 5.4 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:P - Weakness
- CWE-285
- Updated
- 2026-11-02
OSVGHSA-hp6r-r9vc-q8wx
5.4
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.
- Record
GHSA-hp6r-r9vc-q8wx- CVSS 4.0
- 5.4 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:P - CVSS 3.1
- 6.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N - Weakness
- CWE-285
- Updated
- 2026-11-02
OSVPYSEC-2026-1362
5.4
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.
- Record
PYSEC-2026-1362- CVSS 4.0
- 5.4 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:P - CVSS 3.1
- 6.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N - Updated
- 2026-11-02
Affected packages
| Package | Affected | Fixed |
|---|---|---|
fastapi-ssoPyPI |
before 0.19.0 | 0.19.0 |
fastapi-ssoPyPI |
before 0.19.0, plus listed versions 0.10.00.11.00.12.00.12.10.12.2 Show 38 moreShow less0.13.00.13.10.14.00.14.10.14.20.15.00.16.00.17.00.18.00.2.10.2.100.2.110.2.120.2.130.2.20.2.30.2.40.2.50.2.60.2.70.2.80.2.90.3.00.4.00.5.00.5.10.6.10.6.20.6.30.6.40.7.00.7.10.7.20.7.30.7.40.8.00.9.00.9.1 |
0.19.0 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2025-14546 is a medium vulnerability (CVSS 6.9) in fastapi-sso, published December 19, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.36%, the 29th percentile. Fixed in fastapi-sso 0.19.0.
References
security.snyk.io/vuln/SNYK-PYTHON-FASTAPISSO-14386403
github.com/tomasvotava/fastapi-sso/commit/6117d1a5ad498ba57d671e8a059ebe20db5abe02
github.com/tomasvotava/fastapi-sso/issues/266
nvd.nist.gov/vuln/detail/CVE-2025-14546
github.com/advisories/GHSA-hp6r-r9vc-q8wx
github.com/CVEProject/cvelistV5/tree/main/cves/2025/14xxx/CVE-2025-14546.json
github.com/tomasvotava/fastapi-sso
pypi.org/project/fastapi-sso