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.
Metrics
Affected Vendors & Products
Advisories
| Source | ID | Title |
|---|---|---|
Debian DLA |
DLA-2919-1 | python2.7 security update |
Debian DLA |
DLA-3432-1 | python2.7 security update |
Debian DLA |
DLA-3477-1 | python3.7 security update |
Debian DLA |
DLA-3980-1 | python3.9 security update |
EUVD |
EUVD-2021-34049 | 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. |
Ubuntu USN |
USN-5342-1 | Python vulnerabilities |
Ubuntu USN |
USN-5342-2 | Python vulnerabilities |
Ubuntu USN |
USN-6891-1 | Python vulnerabilities |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Mon, 03 Nov 2025 22:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
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Status: PUBLISHED
Assigner: redhat
Published:
Updated: 2025-11-03T21:45:21.395Z
Reserved: 2021-12-29T00:00:00.000Z
Link: CVE-2021-4189
No data.
Status : Modified
Published: 2022-08-24T16:15:09.827
Modified: 2025-11-03T22:15:54.013
Link: CVE-2021-4189
OpenCVE Enrichment
No data.
Debian DLA
EUVD
Ubuntu USN