VulnerabilityAnalyzed

CVE-2025-53539

This vulnerability is fixed in 3.0.1.

MEDIUM 6.9EPSS 0.42%

Does this matter?

Lower severity and a low EPSS score (0.42%). Track it; it rarely justifies an emergency change on its own.

Description

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.

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:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS: 0.42% probability · 36th percentile
CISA KEV: Not listed
Weakness: CWE-1333
Affected: fastapi-guard/fastapi guard
Source: security-advisories@github.com

References

https://github.com/rennf93/fastapi-guard/commit/d9d50e8130b7b434cdc1b001b8cfd03a06729f7fPatch
https://github.com/rennf93/fastapi-guard/security/advisories/GHSA-j47q-rc62-w448Exploit, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.