FKIE_CVE-2021-4189

Vulnerability from fkie_nvd - Published: 2022-08-24 16:15 - Updated: 2026-10-14 11:16
Severity
5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
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.
References
secalert@redhat.comhttps://access.redhat.com/security/cve/CVE-2021-4189Third Party Advisory
secalert@redhat.comhttps://bugs.python.org/issue43285Patch, Vendor Advisory
secalert@redhat.comhttps://bugzilla.redhat.com/show_bug.cgi?id=2036020Issue Tracking, Patch, Third Party Advisory
secalert@redhat.comhttps://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188ePatch, Third Party Advisory
secalert@redhat.comhttps://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
secalert@redhat.comhttps://lists.debian.org/debian-lts-announce/2023/06/msg00039.html
secalert@redhat.comhttps://python-security.readthedocs.io/vuln/ftplib-pasv.htmlPatch, Third Party Advisory
secalert@redhat.comhttps://security-tracker.debian.org/tracker/CVE-2021-4189Third Party Advisory
secalert@redhat.comhttps://security.netapp.com/advisory/ntap-20221104-0004/Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://access.redhat.com/security/cve/CVE-2021-4189Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://bugs.python.org/issue43285Patch, Vendor Advisory
af854a3a-2127-422b-91ae-364da2661108https://bugzilla.redhat.com/show_bug.cgi?id=2036020Issue Tracking, Patch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188ePatch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2023/05/msg00024.html
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2023/06/msg00039.html
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2024/12/msg00000.html
af854a3a-2127-422b-91ae-364da2661108https://python-security.readthedocs.io/vuln/ftplib-pasv.htmlPatch, Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://security-tracker.debian.org/tracker/CVE-2021-4189Third Party Advisory
af854a3a-2127-422b-91ae-364da2661108https://security.netapp.com/advisory/ntap-20221104-0004/Third Party Advisory
0b142b55-0307-4c5a-b3c9-f314f3fb7c5ehttps://cert-portal.siemens.com/productcert/html/ssa-398330.html
Impacted products
Vendor Product Version
python python *
python python *
python python *
python python *
python python 3.10.0
debian debian_linux 10.0
debian debian_linux 11.0
redhat software_collections -
redhat enterprise_linux 8.0
netapp ontap_select_deploy_administration_utility -
To clipboard 

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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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."
    },
    {
      "lang": "es",
      "value": "Se ha encontrado un fallo en Python, concretamente en la biblioteca del cliente FTP (File Transfer Protocol) en modo PASV (pasivo). El problema radica en c\u00f3mo el cliente FTP conf\u00eda en el host a partir de la respuesta PASV por defecto. Este fallo permite a un atacante configurar un servidor FTP malicioso que puede enga\u00f1ar a los clientes FTP para que sean conectados a una direcci\u00f3n IP y un puerto determinados. Esta vulnerabilidad podr\u00eda conllevar a que los clientes FTP escanearan los puertos, lo que de otro modo no habr\u00eda sido posible."
    }
  ],
  "id": "CVE-2021-4189",
  "lastModified": "2026-10-14T11:16:54.940",
  "metrics": {
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        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
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        "impactScore": 1.4,
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          "role": "CISA Coordinator",
          "timestamp": "2025-06-25T14:59:42.470722Z",
          "version": "2.0.3"
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}



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