CVE-2025-53539CWE-1333

ReDoS in fastapi-guard's penetration attempts detector

Medium · published July 7, 2025

CVSS v4.0
6.9
EPSS
0%
Percentile
40.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
6.9 · MEDIUM
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
EPSS
0.00481 · 40.6th percentile
Weakness
CWE-1333 · Inefficient Regular Expression Complexity
Published
2025-07-07T19:16Z
EPSS history
Timeline
  • 07 JUL 19:16Z
    ReDoS in fastapi-guard's penetration attempts detector
    cvelistv5