CVE-2021-4189

Updated: 2025-12-28 04:13:25.406876

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.


Links NIST CIRCL RHEL Ubuntu

Severity

Severity Score
CVSS Version 2.x 0.0
CVSS Version 3.x MEDIUM 5.3

Status

OS name Project name Version Score Severity Status Errata Last updated

Statement

Alpine Linux 3.22 python 3.9 5.3 MEDIUM Not Vulnerable 2026-02-02 14:29:44 Not affected: the environment uses Python 3.9.23, while the PASV host‑trust flaw in ftplib was fix...
Alpine Linux 3.22 python 3.7 5.3 MEDIUM Not Vulnerable 2026-02-16 14:39:47 Not affected: the environment uses Python 3.9.23, while the PASV host‑trust flaw in ftplib was fix...
Alpine Linux 3.22 python 3.8 5.3 MEDIUM Not Vulnerable 2026-02-07 04:07:29 Not affected: the environment uses Python 3.9.23, while the PASV host‑trust flaw in ftplib was fix...
Alpine Linux 3.22 python 3.6 5.3 MEDIUM Not Vulnerable 2026-01-27 16:42:39 Not affected: the environment uses Python 3.9.23, while the PASV host‑trust flaw in ftplib was fix...
Debian 10 python 3.6 5.3 MEDIUM Already Fixed 2025-09-09 19:24:55
Debian 11 python 3.6 5.3 MEDIUM Already Fixed 2025-09-09 19:24:54
Debian 12 python 3.9 5.3 MEDIUM Not Vulnerable 2025-12-11 07:44:24 Not affected: the environment uses Python 3.9.23, while the PASV host‑trust flaw in ftplib was fix...
Debian 12 python 3.7 5.3 MEDIUM Not Vulnerable 2025-12-11 07:45:02 Not affected: the environment uses Python 3.9.23, while the PASV host‑trust flaw in ftplib was fix...
Debian 12 python 3.6 5.3 MEDIUM Already Fixed 2025-09-09 19:24:54 Not affected: the environment uses Python 3.9.23, while the PASV host‑trust flaw in ftplib was fix...
Debian 12 python 3.8 5.3 MEDIUM Not Vulnerable 2025-12-11 07:45:01 Not affected: the environment uses Python 3.9.23, while the PASV host‑trust flaw in ftplib was fix...
Total: 23