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CVE-2021-4189

5.3 · MEDIUM

A flaw was found in Python, specifically in the FTP (File Transfer Protocol) client library in PASV (passive) mode.

Published Aug 24, 2022CWE-252EPSS 3.20%

Overview

CVE-2021-4189 is a medium-severity vulnerability. It was published on August 24, 2022 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refaccess.redhat.com/security/cve/CVE-2021-4189Refbugs.python.org/issue43285Refbugzilla.redhat.com/show_bug.cgi?id=2036020GitHubgithub.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188eReflists.debian.org/debian-lts-announce/2023/05/msg00024.htmlReflists.debian.org/debian-lts-announce/2023/06/msg00039.htmlRefpython-security.readthedocs.io/vuln/ftplib-pasv.htmlRefsecurity-tracker.debian.org/tracker/CVE-2021-4189Refsecurity.netapp.com/advisory/ntap-20221104-0004/Refaccess.redhat.com/security/cve/CVE-2021-4189

How CyberStrike helps

Frequently asked questions

What is CVE-2021-4189?

CVE-2021-4189 is a medium-severity vulnerability. It was published on August 24, 2022 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2021-4189?

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-4189?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-4189?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-4189 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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