Cyber Resilience

CVE-2021-4189

Medium

Published: 24 August 2022

Published
24 August 2022
Modified
17 December 2025
KEV Added
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Patch
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CVSS Score v3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS Score 0.0106 78.0th percentile
Risk Priority 11 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2021-4189 is a medium-severity Unchecked Return Value (CWE-252) vulnerability in Python Python. Its CVSS base score is 5.3 (Medium).

Operationally, ranked in the top 22.0% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

EU & UK References

Vulnerability details

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…

more

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.

CWE(s)
CWE-252

Related Threats

No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.

Affected Assets

python
python
3.10.0 · 3.6.0 — 3.6.14 · 3.7.0 — 3.7.11 · 3.8.0 — 3.8.9
debian
debian linux
10.0, 11.0
redhat
software collections
all versions
redhat
enterprise linux
8.0
netapp
ontap select deploy administration utility
all versions

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References