CVSS 4.0
6.9 mediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:NCVE-2025-53539
Medium (6.9) in fastapi-guard fastapi guard. EPSS 0.5% chance of exploitation in the next 30 days. Fixed in fastapi-guard 3.0.1.
FastAPI Guard is a security library for FastAPI that provides middleware to control IPs, log requests, and detect penetration attempts. fastapi-guard's penetration attempts detection uses regex to scan incoming requests. However, some of the regex patterns used in detection are extremely inefficient and can cause polynomial complexity backtracks when handling specially crafted inputs. This vulnerability is fixed in 3.0.1.
Severity
CVSS 3.1
7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- EPSS
- 0.5% chance of exploitation in the next 30 days; higher than 41% of CVEs (scores of 2026-10-31)
- CWE
- CWE-1333
- Published
- Modified
- Record from
- the NVD, synced
Affected
- fastapi-guard:fastapi_guard
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-j47q-rc62-w448 | PyPI | fastapi-guard | <3.0.1 | 3.0.1 |
| PYSEC-2026-1359 | PyPI | fastapi-guard | <3.0.1 | 3.0.1 |