CVE-2021-4189
MEDIUM severity · CVSS 5.3 · CWE-252
5.3CVSS MEDIUM
Summary
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.
Impact & exploitability
Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
Confidentiality impactLow
Integrity impactNone
Availability impactNone
Exploit probability (EPSS)2%
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Affected products we track (1)
Recommendation
Apply the vendor fix in your normal patch cycle. Open any affected product above for its exact safe version.
Official patch: https://bugs.python.org/issue43285 ↗
Additional information
- NVD record
- https://bugs.python.org/issue43285Patch
- https://bugzilla.redhat.com/show_bug.cgi?id=2036020Patch
- https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188ePatch
- https://python-security.readthedocs.io/vuln/ftplib-pasv.htmlPatch
- https://access.redhat.com/security/cve/CVE-2021-4189Advisory
- https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
- https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html
- https://security-tracker.debian.org/tracker/CVE-2021-4189Advisory