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CVE-2021-4189

Published: Aug 24, 2022Updated: Dec 17, 2025 Sources: CVE List NVD BDU csafCWE-252
5.3MEDIUM
NVD MITRE
EPSS Score
2.7%
Top 15.8%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:LI:NA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:LConfidentiality
Low
I:NIntegrity
None
A:NAvailability
None
Open in CVSS calculator →

Weaknesses

CWE-252

Affected Products

Red Hat Inc.
commercial·USaka redhat, red hat
Red Hat Enterprise LinuxOn-premOS
Operating Systems / linux-distro
Red Hat Software CollectionsOn-prem
Operating Systems / linux-distro
software collectionsOn-prem
Operating Systems / linux-distro
Сообщество свободного программного обеспечения
oss-projectaka fsf
Debian GNU/LinuxOn-premOS
Operating Systems / linux-distro
Canonical Ltd.
commercial·GBaka canonical
UbuntuOn-premOS
Operating Systems / linux-distro
ООО «РусБИТех-Астра»
commercial·RUaka rusbitech-astra
Astra Linux Special EditionOn-premOS
Operating Systems / linux-distro
Fedora Project
oss-project·USaka fedora
FedoraOn-premOS
Operating Systems / linux-distro
Python Software Foundation
oss-project·USaka psf
PythonLibraryLibrary
OSS Libraries
and 8 more affected products View all →

Exploitability

Official Patch Available
Is your org exposed to CVE-2021-4189?We can run the check for you — a free external exposure review, no install. Check my exposure

References

https://bugs.python.org/issue43285
bugs.python.org
https://python-security.readthedocs.io/vuln/ftplib-pasv.html
python-security.readthedocs.io
https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e
github.com
and 33 more references View all →

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