CVE-2025-53539

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 v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/rennf93/fastapi-guard/commit/d9d50e8130b7b434cdc1b001b8cfd03a06729f7f	Patch
https://github.com/rennf93/fastapi-guard/security/advisories/GHSA-j47q-rc62-w448	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:fastapi-guard:fastapi_guard:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2025-07-07 20:15

Updated : 2025-12-31 17:05

NVD link : CVE-2025-53539

Mitre link : CVE-2025-53539

CVE.ORG link : CVE-2025-53539

JSON object : View

Products Affected

fastapi-guard

fastapi_guard

CWE

CWE-1333

Inefficient Regular Expression Complexity

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