Medium severity5.3NVD Advisory· Published Aug 24, 2022· Updated Jun 17, 2026
CVE-2021-4189
CVE-2021-4189
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
113- Python/FTP client librarydescription
- osv-coords111 versionspkg:bitnami/libpythonpkg:bitnami/pythonpkg:bitnami/python-minpkg:rpm/almalinux/babelpkg:rpm/almalinux/platform-pythonpkg:rpm/almalinux/platform-python-debugpkg:rpm/almalinux/platform-python-develpkg:rpm/almalinux/python2pkg:rpm/almalinux/python2-attrspkg:rpm/almalinux/python2-babelpkg:rpm/almalinux/python2-backportspkg:rpm/almalinux/python2-backports-ssl_match_hostnamepkg:rpm/almalinux/python2-bsonpkg:rpm/almalinux/python2-chardetpkg:rpm/almalinux/python2-coveragepkg:rpm/almalinux/python2-Cythonpkg:rpm/almalinux/python2-debugpkg:rpm/almalinux/python2-develpkg:rpm/almalinux/python2-dnspkg:rpm/almalinux/python2-docspkg:rpm/almalinux/python2-docs-infopkg:rpm/almalinux/python2-docutilspkg:rpm/almalinux/python2-funcsigspkg:rpm/almalinux/python2-idnapkg:rpm/almalinux/python2-ipaddresspkg:rpm/almalinux/python2-jinja2pkg:rpm/almalinux/python2-libspkg:rpm/almalinux/python2-lxmlpkg:rpm/almalinux/python2-markupsafepkg:rpm/almalinux/python2-mockpkg:rpm/almalinux/python2-nosepkg:rpm/almalinux/python2-numpypkg:rpm/almalinux/python2-numpy-docpkg:rpm/almalinux/python2-numpy-f2pypkg:rpm/almalinux/python2-pippkg:rpm/almalinux/python2-pip-wheelpkg:rpm/almalinux/python2-pluggypkg:rpm/almalinux/python2-psycopg2pkg:rpm/almalinux/python2-psycopg2-debugpkg:rpm/almalinux/python2-psycopg2-testspkg:rpm/almalinux/python2-pypkg:rpm/almalinux/python2-pygmentspkg:rpm/almalinux/python2-pymongopkg:rpm/almalinux/python2-pymongo-gridfspkg:rpm/almalinux/python2-PyMySQLpkg:rpm/almalinux/python2-pysockspkg:rpm/almalinux/python2-pytestpkg:rpm/almalinux/python2-pytest-mockpkg:rpm/almalinux/python2-pytzpkg:rpm/almalinux/python2-pyyamlpkg:rpm/almalinux/python2-requestspkg:rpm/almalinux/python2-rpm-macrospkg:rpm/almalinux/python2-scipypkg:rpm/almalinux/python2-setuptoolspkg:rpm/almalinux/python2-setuptools_scmpkg:rpm/almalinux/python2-setuptools-wheelpkg:rpm/almalinux/python2-sixpkg:rpm/almalinux/python2-sqlalchemypkg:rpm/almalinux/python2-testpkg:rpm/almalinux/python2-tkinterpkg:rpm/almalinux/python2-toolspkg:rpm/almalinux/python2-urllib3pkg:rpm/almalinux/python2-virtualenvpkg:rpm/almalinux/python2-wheelpkg:rpm/almalinux/python2-wheel-wheelpkg:rpm/almalinux/python3-idlepkg:rpm/almalinux/python3-libspkg:rpm/almalinux/python3-testpkg:rpm/almalinux/python3-tkinterpkg:rpm/almalinux/python-nose-docspkg:rpm/almalinux/python-psycopg2-docpkg:rpm/almalinux/python-sqlalchemy-docpkg:rpm/opensuse/python315&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/python-base&distro=openSUSE%20Leap%2015.3pkg:rpm/opensuse/python&distro=openSUSE%20Leap%2015.3pkg:rpm/opensuse/python&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/python-doc&distro=openSUSE%20Leap%2015.3pkg:rpm/suse/python3-base&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Web%20and%20Scripting%2012pkg:rpm/suse/python3-base&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP5pkg:rpm/suse/python3-base&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2012%20SP5pkg:rpm/suse/python3-base&distro=SUSE%20Linux%20Enterprise%20Software%20Development%20Kit%2012%20SP5pkg:rpm/suse/python3&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Web%20and%20Scripting%2012pkg:rpm/suse/python3&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP5pkg:rpm/suse/python3&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2012%20SP5pkg:rpm/suse/python3&distro=SUSE%20Linux%20Enterprise%20Software%20Development%20Kit%2012%20SP5pkg:rpm/suse/python-base&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Basesystem%2015%20SP3pkg:rpm/suse/python-base&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Python%202%2015%20SP3pkg:rpm/suse/python-base&distro=SUSE%20Linux%20Enterprise%20Real%20Time%2015%20SP2pkg:rpm/suse/python-base&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP4-LTSSpkg:rpm/suse/python-base&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP5pkg:rpm/suse/python-base&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2012%20SP4pkg:rpm/suse/python-base&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2012%20SP5pkg:rpm/suse/python-base&distro=SUSE%20Linux%20Enterprise%20Workstation%20Extension%2012%20SP5pkg:rpm/suse/python-base&distro=SUSE%20OpenStack%20Cloud%209pkg:rpm/suse/python-base&distro=SUSE%20OpenStack%20Cloud%20Crowbar%209pkg:rpm/suse/python&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Basesystem%2015%20SP3pkg:rpm/suse/python&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Desktop%20Applications%2015%20SP3pkg:rpm/suse/python&distro=SUSE%20Linux%20Enterprise%20Module%20for%20Python%202%2015%20SP3pkg:rpm/suse/python&distro=SUSE%20Linux%20Enterprise%20Real%20Time%2015%20SP2pkg:rpm/suse/python&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP4-LTSSpkg:rpm/suse/python&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP5pkg:rpm/suse/python&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2012%20SP4pkg:rpm/suse/python&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2012%20SP5pkg:rpm/suse/python&distro=SUSE%20OpenStack%20Cloud%209pkg:rpm/suse/python&distro=SUSE%20OpenStack%20Cloud%20Crowbar%209pkg:rpm/suse/python-doc&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP4-LTSSpkg:rpm/suse/python-doc&distro=SUSE%20Linux%20Enterprise%20Server%2012%20SP5pkg:rpm/suse/python-doc&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2012%20SP4pkg:rpm/suse/python-doc&distro=SUSE%20Linux%20Enterprise%20Server%20for%20SAP%20Applications%2012%20SP5pkg:rpm/suse/python-doc&distro=SUSE%20OpenStack%20Cloud%209pkg:rpm/suse/python-doc&distro=SUSE%20OpenStack%20Cloud%20Crowbar%209
>= 3.6.0, < 3.6.14+ 110 more
- (no CPE)range: >= 3.6.0, < 3.6.14
- (no CPE)range: >= 3.6.0, < 3.6.14
- (no CPE)range: >= 3.6.0, < 3.6.14
- (no CPE)range: < 2.5.1-10.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 3.6.8-45.el8.alma
- (no CPE)range: < 3.6.8-45.el8.alma
- (no CPE)range: < 3.6.8-45.el8.alma
- (no CPE)range: < 2.7.18-10.module_el8.6.0+2781+fed64c13.alma
- (no CPE)range: < 17.4.0-10.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.5.1-10.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.0-16.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 3.5.0.1-12.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 3.7.0-1.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 3.0.4-10.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 4.5.1-4.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 0.28.1-7.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.7.18-10.module_el8.6.0+2781+fed64c13.alma
- (no CPE)range: < 2.7.18-10.module_el8.6.0+2781+fed64c13.alma
- (no CPE)range: < 1.15.0-10.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.7.16-2.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.7.16-2.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 0.14-12.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.0.2-13.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.5-7.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.0.18-6.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.10-9.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.7.18-10.module_el8.6.0+2781+fed64c13.alma
- (no CPE)range: < 4.2.3-6.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 0.23-19.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.0.0-13.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.3.7-31.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1:1.14.2-16.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1:1.14.2-16.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1:1.14.2-16.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 9.0.3-19.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 9.0.3-19.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 0.6.0-8.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.7.5-7.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.7.5-7.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.7.5-7.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.5.3-6.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.2.0-22.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 3.7.0-1.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 3.7.0-1.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 0.8.0-10.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.6.8-6.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 3.4.2-13.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.9.0-4.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2017.2-12.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 3.12-16.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.20.0-3.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 3-38.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.0.0-21.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 39.0.1-13.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.15.7-6.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 39.0.1-13.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.11.0-6.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.3.2-2.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.7.18-10.module_el8.6.0+2781+fed64c13.alma
- (no CPE)range: < 2.7.18-10.module_el8.6.0+2781+fed64c13.alma
- (no CPE)range: < 2.7.18-10.module_el8.6.0+2781+fed64c13.alma
- (no CPE)range: < 1.24.2-3.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 15.1.0-21.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1:0.31.1-3.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1:0.31.1-3.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 3.6.8-45.el8.alma
- (no CPE)range: < 3.6.8-45.el8.alma
- (no CPE)range: < 3.6.8-45.el8.alma
- (no CPE)range: < 3.6.8-45.el8.alma
- (no CPE)range: < 1.3.7-31.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 2.7.5-7.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 1.3.2-2.module_el8.6.0+2781+fed64c13
- (no CPE)range: < 3.15.0~b2-1.1
- (no CPE)range: < 2.7.18-150000.38.2
- (no CPE)range: < 2.7.18-150000.38.1
- (no CPE)range: < 2.7.18-15.1
- (no CPE)range: < 2.7.18-150000.38.1
- (no CPE)range: < 3.4.10-25.85.1
- (no CPE)range: < 3.4.10-25.85.1
- (no CPE)range: < 3.4.10-25.85.1
- (no CPE)range: < 3.4.10-25.85.1
- (no CPE)range: < 3.4.10-25.85.2
- (no CPE)range: < 3.4.10-25.85.2
- (no CPE)range: < 3.4.10-25.85.2
- (no CPE)range: < 3.4.10-25.85.2
- (no CPE)range: < 2.7.18-150000.38.2
- (no CPE)range: < 2.7.18-150000.38.2
- (no CPE)range: < 2.7.18-150000.38.2
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-150000.38.1
- (no CPE)range: < 2.7.18-150000.38.1
- (no CPE)range: < 2.7.18-150000.38.1
- (no CPE)range: < 2.7.18-150000.38.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
- (no CPE)range: < 2.7.18-33.8.1
Patches
Vulnerability mechanics
References
10- bugs.python.org/issue43285nvdPatchVendor Advisory
- bugzilla.redhat.com/show_bug.cginvdIssue TrackingPatchThird Party Advisory
- github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188envdPatchThird Party Advisory
- python-security.readthedocs.io/vuln/ftplib-pasv.htmlnvdPatchThird Party Advisory
- access.redhat.com/security/cve/CVE-2021-4189nvdThird Party Advisory
- security-tracker.debian.org/tracker/CVE-2021-4189nvdThird Party Advisory
- security.netapp.com/advisory/ntap-20221104-0004/nvdThird Party Advisory
- lists.debian.org/debian-lts-announce/2023/05/msg00024.htmlnvd
- lists.debian.org/debian-lts-announce/2023/06/msg00039.htmlnvd
- lists.debian.org/debian-lts-announce/2024/12/msg00000.htmlnvd
News mentions
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