CVE-2021-4189

  1. OpenCVE
  2. Vulnerabilities (CVE)
  3. CVE-2021-4189
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.

5.3 /10

CVSS v3 : MEDIUM

V3 Legend

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References
Link Resource
https://access.redhat.com/security/cve/CVE-2021-4189 Third Party Advisory
https://bugs.python.org/issue43285 Patch Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2036020 Issue Tracking Patch Third Party Advisory
https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html
https://python-security.readthedocs.io/vuln/ftplib-pasv.html Patch Third Party Advisory
https://security-tracker.debian.org/tracker/CVE-2021-4189 Third Party Advisory
https://security.netapp.com/advisory/ntap-20221104-0004/ Third Party Advisory
https://access.redhat.com/security/cve/CVE-2021-4189 Third Party Advisory
https://bugs.python.org/issue43285 Patch Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2036020 Issue Tracking Patch Third Party Advisory
https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html
https://lists.debian.org/debian-lts-announce/2024/12/msg00000.html
https://python-security.readthedocs.io/vuln/ftplib-pasv.html Patch Third Party Advisory
https://security-tracker.debian.org/tracker/CVE-2021-4189 Third Party Advisory
https://security.netapp.com/advisory/ntap-20221104-0004/ Third Party Advisory
Configurations

Configuration 1 (hide)

OR cpe:2.3:a:python:python:*:*:*:*:*:*:*:*
cpe:2.3:a:python:python:*:*:*:*:*:*:*:*
cpe:2.3:a:python:python:*:*:*:*:*:*:*:*
cpe:2.3:a:python:python:*:*:*:*:*:*:*:*
cpe:2.3:a:python:python:3.10.0:-:*:*:*:*:*:*

Configuration 2 (hide)

OR cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

Configuration 3 (hide)

OR cpe:2.3:a:redhat:software_collections:-:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*

Configuration 4 (hide)

cpe:2.3:a:netapp:ontap_select_deploy_administration_utility:-:*:*:*:*:*:*:*
History

03 Nov 2025, 22:15

Type Values Removed Values Added
References
  • () https://lists.debian.org/debian-lts-announce/2024/12/msg00000.html -

21 Nov 2024, 06:37

Type Values Removed Values Added
References () https://access.redhat.com/security/cve/CVE-2021-4189 - Third Party Advisory () https://access.redhat.com/security/cve/CVE-2021-4189 - Third Party Advisory
References () https://bugs.python.org/issue43285 - Patch, Vendor Advisory () https://bugs.python.org/issue43285 - Patch, Vendor Advisory
References () https://bugzilla.redhat.com/show_bug.cgi?id=2036020 - Issue Tracking, Patch, Third Party Advisory () https://bugzilla.redhat.com/show_bug.cgi?id=2036020 - Issue Tracking, Patch, Third Party Advisory
References () https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e - Patch, Third Party Advisory () https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e - Patch, Third Party Advisory
References () https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html - () https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html -
References () https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html - () https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html -
References () https://python-security.readthedocs.io/vuln/ftplib-pasv.html - Patch, Third Party Advisory () https://python-security.readthedocs.io/vuln/ftplib-pasv.html - Patch, Third Party Advisory
References () https://security-tracker.debian.org/tracker/CVE-2021-4189 - Third Party Advisory () https://security-tracker.debian.org/tracker/CVE-2021-4189 - Third Party Advisory
References () https://security.netapp.com/advisory/ntap-20221104-0004/ - Third Party Advisory () https://security.netapp.com/advisory/ntap-20221104-0004/ - Third Party Advisory

30 Jun 2023, 23:15

Type Values Removed Values Added
References
  • (MLIST) https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html -

24 May 2023, 21:15

Type Values Removed Values Added
References
  • (MLIST) https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html -
Information

Published : 2022-08-24 16:15

Updated : 2025-11-03 22:15

NVD link : CVE-2021-4189

Mitre link : CVE-2021-4189

CVE.ORG link : CVE-2021-4189

JSON object : View

Products Affected

redhat

  • enterprise_linux
  • software_collections

python

  • python

debian

  • debian_linux

netapp

  • ontap_select_deploy_administration_utility
CWE
CWE-252

Unchecked Return Value