CVE & CISA-KEV Catalog

CVE-2021-4189

MEDIUMEPSS 83th pctl
5.3
CVSS v3
NVD

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.

CWE-252

How to fix

Remediation Available
pypy3Debian
Fixed in:7.3.5+dfsg-2CVE-2021-4189
Fixed in:7.3.5+dfsg-2CVE-2021-4189
Fixed in:7.3.5+dfsg-2CVE-2021-4189
Fixed in:7.3.5+dfsg-2CVE-2021-4189
python2.7Ubuntu
Fixed in:2.7.6-8ubuntu0.6+esm12USN-5342-2
Fixed in:2.7.12-1ubuntu0~16.04.18+esm1USN-5342-1
Fixed in:2.7.17-1~18.04ubuntu1.7USN-5342-1
Fixed in:2.7.18-1~20.04.3+esm1USN-5342-2
Fixed in:2.7.18-13ubuntu1.1+esm2USN-5342-2
python2.7-minimalUbuntu
Fixed in:2.7.6-8ubuntu0.6+esm12USN-5342-2
Fixed in:2.7.12-1ubuntu0~16.04.18+esm1USN-5342-1
Fixed in:2.7.17-1~18.04ubuntu1.7USN-5342-1
Fixed in:2.7.18-1~20.04.3+esm1USN-5342-2
Fixed in:2.7.18-13ubuntu1.1+esm2USN-5342-2
python3.10Ubuntu
Fixed in:3.10.12-1~22.04.4USN-6891-1
python3.10-minimalUbuntu
Fixed in:3.10.12-1~22.04.4USN-6891-1
python3.11Ubuntu
Fixed in:3.11.0~rc1-1~22.04.1~esm1USN-6891-1
Fixed in:3.11.6-3ubuntu0.1USN-6891-1
python3.11-minimalUbuntu
Fixed in:3.11.0~rc1-1~22.04.1~esm1USN-6891-1
Fixed in:3.11.6-3ubuntu0.1USN-6891-1
python3.12Ubuntu
Fixed in:3.12.0-1ubuntu0.1USN-6891-1
python3.12-minimalUbuntu
Fixed in:3.12.0-1ubuntu0.1USN-6891-1
python3.4Ubuntu
Fixed in:3.4.3-1ubuntu1~14.04.7+esm12USN-5342-1
python3.4-minimalUbuntu
Fixed in:3.4.3-1ubuntu1~14.04.7+esm12USN-5342-1
python3.5Ubuntu
Fixed in:3.5.2-2ubuntu0~16.04.4~14.04.1+esm1USN-6891-1
Fixed in:3.5.2-2ubuntu0~16.04.13+esm13USN-6891-1
Fixed in:3.5.2-2ubuntu0~16.04.13+esm2USN-5342-1
python3.5-minimalUbuntu
Fixed in:3.5.2-2ubuntu0~16.04.4~14.04.1+esm1USN-6891-1
Fixed in:3.5.2-2ubuntu0~16.04.13+esm13USN-6891-1
Fixed in:3.5.2-2ubuntu0~16.04.13+esm2USN-5342-1
python3.6Ubuntu
Fixed in:3.6.9-1~18.04ubuntu1.7USN-5342-1
Fixed in:3.6.9-1~18.04ubuntu1.13+esm2USN-6891-1
python3.6-minimalUbuntu
Fixed in:3.6.9-1~18.04ubuntu1.13+esm2USN-6891-1
Fixed in:3.6.9-1~18.04ubuntu1.7USN-5342-1
python3.7Ubuntu
Fixed in:3.7.5-2ubuntu1~18.04.2+esm3USN-6891-1
python3.7-minimalUbuntu
Fixed in:3.7.5-2ubuntu1~18.04.2+esm3USN-6891-1
python3.8Ubuntu
Fixed in:3.8.0-3ubuntu1~18.04.2+esm2USN-6891-1
Fixed in:3.8.10-0ubuntu1~20.04.10USN-6891-1
Fixed in:3.8.10-0ubuntu1~20.04.4USN-5342-1
python3.8-minimalUbuntu
Fixed in:3.8.0-3ubuntu1~18.04.2+esm2USN-6891-1
Fixed in:3.8.10-0ubuntu1~20.04.10USN-6891-1
Fixed in:3.8.10-0ubuntu1~20.04.4USN-5342-1
python3.9Ubuntu
Fixed in:3.9.5-3ubuntu0~20.04.1+esm2USN-6891-1
python3.9-minimalUbuntu
Fixed in:3.9.5-3ubuntu0~20.04.1+esm2USN-6891-1
Python 2Windows application
Affected:3.9.0 3.9.3Fixed in:3.9.3Python Software Foundation
Affected:3.8.0 3.8.9Fixed in:3.8.9Python Software Foundation
Affected:3.7.0 3.7.11Fixed in:3.7.11Python Software Foundation
Affected:3.6.0 3.6.14Fixed in:3.6.14Python Software Foundation
Python 3.10Windows application
Affected:3.6.0 3.6.14Fixed in:3.6.14Python Software Foundation
Affected:3.9.0 3.9.3Fixed in:3.9.3Python Software Foundation
Affected:3.7.0 3.7.11Fixed in:3.7.11Python Software Foundation
Affected:3.8.0 3.8.9Fixed in:3.8.9Python Software Foundation
Python 3.11Windows application
Affected:3.7.0 3.7.11Fixed in:3.7.11Python Software Foundation
Affected:3.9.0 3.9.3Fixed in:3.9.3Python Software Foundation
Affected:3.6.0 3.6.14Fixed in:3.6.14Python Software Foundation
Affected:3.8.0 3.8.9Fixed in:3.8.9Python Software Foundation
Python 3.12Windows application
Affected:3.6.0 3.6.14Fixed in:3.6.14Python Software Foundation
Affected:3.9.0 3.9.3Fixed in:3.9.3Python Software Foundation
Affected:3.8.0 3.8.9Fixed in:3.8.9Python Software Foundation
Affected:3.7.0 3.7.11Fixed in:3.7.11Python Software Foundation
Python 3.8Windows application
Affected:3.9.0 3.9.3Fixed in:3.9.3Python Software Foundation
Affected:3.6.0 3.6.14Fixed in:3.6.14Python Software Foundation
Affected:3.8.0 3.8.9Fixed in:3.8.9Python Software Foundation
Affected:3.7.0 3.7.11Fixed in:3.7.11Python Software Foundation
Python 3.9Windows application
Affected:3.7.0 3.7.11Fixed in:3.7.11Python Software Foundation
Affected:3.9.0 3.9.3Fixed in:3.9.3Python Software Foundation
Affected:3.8.0 3.8.9Fixed in:3.8.9Python Software Foundation
Affected:3.6.0 3.6.14Fixed in:3.6.14Python Software Foundation

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityLow
IntegrityNone
AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Exploit Intelligence

2.51%probability of exploitation in 30 days
83rdpercentile

Elevated risk: more likely to be exploited than 83% of all known CVEs.

References

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Markdown

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-12-17.