High severity7.5NVD Advisory· Published Jul 7, 2025· Updated Jun 17, 2026
CVE-2025-53539
CVE-2025-53539
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.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
fastapi-guardPyPI | < 3.0.1 | 3.0.1 |
Affected products
3- Range: < 3.0.1
Patches
Vulnerability mechanics
References
4- github.com/rennf93/fastapi-guard/commit/d9d50e8130b7b434cdc1b001b8cfd03a06729f7fnvdPatchWEB
- github.com/rennf93/fastapi-guard/security/advisories/GHSA-j47q-rc62-w448nvdExploitVendor AdvisoryWEB
- github.com/advisories/GHSA-j47q-rc62-w448ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2025-53539ghsaADVISORY
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