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CVE-2021-4189

Updated on 24 Aug 2022

Severity

5.3 Medium severity

Details

CVSS score
5.3
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE ID
Links
NISTCIRCLRHELUbuntu

Overview

About vulnerability

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.

Details

Affected product:
Alpine Linux 3.22 , CentOS 6 ELS , CentOS 7 ELS , CentOS 8.4 ELS , CentOS 8.5 ELS , CloudLinux 6 ELS , Debian 10 , Debian 11 , Debian 12 , Debian 13 , EL 10 , EL 6 , EL 7 , EL 8 , EL 9 , Oracle Linux 6 ELS , Ubuntu 16.04 , Ubuntu 16.04 ELS , Ubuntu 18.04 , Ubuntu 18.04 ELS , Ubuntu 20.04 , Ubuntu 22.04 , Ubuntu 24.04
Affected packages:
python2.7 @ 2.7.12 (+35 more)
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.

Fixes