CVE-2021-4189

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.

Affected Software

Weaknesses

• Not-Known

ADP Enrichment

CVE Program Container

Additional 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/
• https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
• https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html
• https://lists.debian.org/debian-lts-announce/2024/12/msg00000.html

CISA ADP Vulnrichment

• SSVC:
• Exploitation: none
  • Automatable: yes
  • Technical Impact: partial

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/
• https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
• https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html

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