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CVE-2025-53539mediumCWE-1333

ReDoS in fastapi-guard's penetration attempts detector

13Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 6.9epss 0.4%
exploitation probability
0.4%top 65% of all CVEs
observed exploitation
nono source reports it
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/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
Affected products
rennf93 · fastapi-guard