{"cve":"CVE-2021-4189","nvd":{"published":"2022-08-24T16:15:09.827","modified":"2026-10-14T11:16:54.940","status":"Modified","description":"A flaw was found in Python, specifically in the FTP (File Transfer Protocol) client library in PASV (passive) mode. The issue is how the FTP client trusts the host from the PASV response by default. This flaw allows an attacker to set up a malicious FTP server that can trick FTP clients into connecting back to a given IP address and port. This vulnerability could lead to FTP client scanning ports, which otherwise would not have been possible.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N","score":5.3},"cwes":["CWE-252"],"references":["https://access.redhat.com/security/cve/CVE-2021-4189","https://bugs.python.org/issue43285","https://bugzilla.redhat.com/show_bug.cgi?id=2036020","https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e","https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html"],"products":["debian:debian_linux","netapp:ontap_select_deploy_administration_utility","python:python","redhat:enterprise_linux","redhat:software_collections"],"source":"nvd","synced_at":"2026-10-19T21:34:18.502168378+00:00"},"epss":{"cve":"CVE-2021-4189","score":0.03409,"percentile":0.88788,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}