CVE-2021-4189
Estado: ModificadaMedia (5.3)—
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.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- Puntuación base: 5.3
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 3.20%
- Percentil entre todas las CVEs puntuadas: 88
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (5)
CWE
- CWE-252
- CWE-252
Referencias
- https://access.redhat.com/security/cve/CVE-2021-4189
- https://bugs.python.org/issue43285
- https://bugzilla.redhat.com/show_bug.cgi?id=2036020
- https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e
- https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
- https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html
- https://python-security.readthedocs.io/vuln/ftplib-pasv.html
- https://security-tracker.debian.org/tracker/CVE-2021-4189
- https://security.netapp.com/advisory/ntap-20221104-0004/
- https://access.redhat.com/security/cve/CVE-2021-4189
- https://bugs.python.org/issue43285
- https://bugzilla.redhat.com/show_bug.cgi?id=2036020
- https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e
- 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
- https://python-security.readthedocs.io/vuln/ftplib-pasv.html
- https://security-tracker.debian.org/tracker/CVE-2021-4189
- https://security.netapp.com/advisory/ntap-20221104-0004/
JSON original (NVD)
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