CVE-2021-4189
- State
- Published
- Severity
- 5.3 Medium
- Published
- Aug 24, 2022
- Updated
- Oct 14, 2026
- Reserved
- Dec 29, 2021
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.3 Medium | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N | CISA-ADP |
Weaknesses
- CWE-252 Unchecked Return Value
Affected Products
| Product | Versions |
|---|---|
pythonn/a |
|
References
- https://bugs.python.org/issue43285
- https://python-security.readthedocs.io/vuln/ftplib-pasv.html
- https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e
- https://security-tracker.debian.org/tracker/CVE-2021-4189
- https://bugzilla.redhat.com/show_bug.cgi?id=2036020
- https://access.redhat.com/security/cve/CVE-2021-4189
- https://security.netapp.com/advisory/ntap-20221104-0004/
- [debian-lts-announce] 20230524 [SECURITY] [DLA 3432-1] python2.7 security updatemailing-list
- [debian-lts-announce] 20230630 [SECURITY] [DLA 3477-1] python3.7 security updatemailing-list
- https://lists.debian.org/debian-lts-announce/2024/12/msg00000.html
- https://cert-portal.siemens.com/productcert/html/ssa-398330.html
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