01 Record

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.

MediumPUBLISHEDCNA: redhat

CNA base score5.3 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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02 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.

03 Exploitation and scoring

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

3.20% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 87.1% of scored records. A rank, not a probability.

NVD base score

5.3 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

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

NVD analysis status

Modified. NVD last modified this record on 2026-06-17.

Red Hat severity

Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published

2022-08-24 00:00Z4 YR AGO

Last updated

2025-12-17 21:36Z8 MO AGO

Reserved

2021-12-29

Assigning CNA

redhat

Record state

PUBLISHED

Severity

Medium (CVSS 5.3)

CNA CVSS vector

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

Weaknesses

CWE-252Unchecked Return ValueBase

Data version

5.2

Document digest

bc338bd687797ce9ab4d6c9e30c4d1ced195389562732646c229949a97fe9a34

05 Affected products

VendorProductVersionsPlatforms

n/apythonFixed in python 3.6.14, python 3.7.11, python 3.8.9, python 3.9.3, python 3.10.0—

06 References

bugs.python.orghttps://bugs.python.org/issue43285
python-security.readthedocs.iohttps://python-security.readthedocs.io/vuln/ftplib-pasv.html
github.comhttps://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e
security-tracker.debian.orghttps://security-tracker.debian.org/tracker/CVE-2021-4189
bugzilla.redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=2036020
access.redhat.comhttps://access.redhat.com/security/cve/CVE-2021-4189
security.netapp.comhttps://security.netapp.com/advisory/ntap-20221104-0004/
lists.debian.org[debian-lts-announce] 20230524 [SECURITY] [DLA 3432-1] python2.7 security updatehttps://lists.debian.org/debian-lts-announce/2023/05/msg00024.htmlmailing-list
lists.debian.org[debian-lts-announce] 20230630 [SECURITY] [DLA 3477-1] python3.7 security updatehttps://lists.debian.org/debian-lts-announce/2023/06/msg00039.htmlmailing-list
lists.debian.orghttps://lists.debian.org/debian-lts-announce/2024/12/msg00000.html

01 Record index

CVE-2021-4189

02 Description

03 Exploitation and scoring

04 Metadata

05 Affected products

06 References

02 Records

CVE-2021-4189

02 Description

03 Exploitation and scoring

04 Metadata

05 Affected products

06 References