CVE-2025-53539

MEDIUM EPSS 33.9%
Published Jul 7, 202511mo ago · Modified Jun 17, 20261w ago
6.9 CVSS 4.0
Medium
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Published Jul 7, 2025 11mo ago
Last Modified Jun 17, 2026 1w ago

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 Details

Base Score
6.9
Exploitability
—
Impact
—
Vector string
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/E:X/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
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope X

Threat Intelligence

EPSS Exploit Probability
33.9% percentile
Exploit & Patch Status
Public Exploit Known
Patch Available

Weaknesses 1

CWE-1333

Affected Products 1

VendorProductVersionRange
fastapi-guardfastapi_guard* <3.0.1

References 2

  • github.com https://github.com/rennf93/fastapi-guard/commit/d9d50e8130b7b434cdc1b001b8cfd03a06729f7f
    Patch
  • github.com https://github.com/rennf93/fastapi-guard/security/advisories/GHSA-j47q-rc62-w448
    ExploitVendor Advisory

Remediation

  • github.com https://github.com/rennf93/fastapi-guard/commit/d9d50e8130b7b434cdc1b001b8cfd03a06729f7f
    Patch