CVE-2025-14546 json
FastAPI SSP is vulnerable to Cross-site Request Forgery (CSRF) through improper OAuth parameter validation
published 2025-12-19 10 mo ago modified 2026-10-13 26 d ago also GHSA-hp6r-r9vc-q8wx , PYSEC-2026-1362 , EUVD-2025-204438
- cvss
- 6.3
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 29%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 10 mo ago
Exploit prediction
0.36% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 6.9 | 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 |
| CNA | 3.1 | 6.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N/E:P |
| CNA | 4.0 | 5.4 | 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 |
| CNA | 3.1 | 6.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N |
| OSV | 3.1 | 6.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N |
| GitHub | 3.1 | 6.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | fastapi-sso | <0.19.0 |
0.19.0 |
Affected products
- n/a fastapi-sso
Classification
- Weakness
-
- CWE-285 Improper Authorization
References
-
github.com
/tomasvotava/fastapi-sso/commit/6117d1a5ad498ba57d671e8a059ebe20db5abe02
web
-
security.snyk.io
/vuln/SNYK-PYTHON-FASTAPISSO-14386403
web
-
github.com
/tomasvotava/fastapi-sso/issues/266
web
-
nvd.nist.gov
/vuln/detail/CVE-2025-14546
advisory
-
github.com
/tomasvotava/fastapi-sso
package
-
pypi.org
/project/fastapi-sso
package
-
github.com
/advisories/GHSA-hp6r-r9vc-q8wx
advisory
Sources
- CVE List CVE-2025-14546
- GitHub Advisory GHSA-hp6r-r9vc-q8wx
- NVD CVE-2025-14546
- OSV PYSEC-2026-1362
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