View at Official debian advisory, NVD, CVE.org · CVE detail
Freshness: upstream tracker timestamp is available; use API updated time as primary recency signal.
CVE-2021-4189 not yet assigned priority: Debian including 3 source packages (pypy3, python2.7, python3.9), 7 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6, open 1.
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.