UBUNTU-CVE-2021-4189

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    UBUNTU-CVE-2021-4189

    Published: 31 Dec 2021Last Modified: 6 Jul 2026
    Upstream:
    CVE-2021-4189
    Aliases:
    USN-5342-1
    USN-5342-2
    USN-6891-1

    Summary:

    Details: 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: https://ubuntu.com/security/CVE-2021-4189, https://bugs.python.org/issue43285, https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e, https://github.com/python/cpython/commit/7dcb4baa4f0fde3aef5122a8e9f6a41853ec9335, https://github.com/python/cpython/commit/79373951b3eab585d42e0f0ab83718cbe1d0ee33, https://github.com/python/cpython/commit/4134f154ae2f621f25c5d698cc0f1748035a1b88, https://bugzilla.redhat.com/show_bug.cgi?id=2036020, https://ubuntu.com/security/notices/USN-5342-1, https://ubuntu.com/security/notices/USN-5342-2, https://www.cve.org/CVERecord?id=CVE-2021-4189, https://ubuntu.com/security/notices/USN-6891-1, https://ubuntu.com/security/notices/USN-8509-1

    Affected packages

    Package

    Name: python2.7

    Purl: pkg:deb/ubuntu/python2.7?arch=source&distro=trusty%2Fesm

    Affected ranges

    Type: ECOSYSTEM

    Events:

    Introduced- 0
    Fixed -2.7.6-8ubuntu0.6+esm12

    Affected versions

    2.7.5-8ubuntu3
    2.7.5-8ubuntu4
    2.7.6-2
    2.7.6-2ubuntu1
    2.7.6-3
    2.7.6-3ubuntu1
    2.7.6-4
    2.7.6-4ubuntu1
    2.7.6-5
    2.7.6-7
    2.7.6-8
    2.7.6-8ubuntu0.2
    2.7.6-8ubuntu0.3
    2.7.6-8ubuntu0.4
    2.7.6-8ubuntu0.5
    2.7.6-8ubuntu0.6+esm2
    2.7.6-8ubuntu0.6+esm3
    2.7.6-8ubuntu0.6+esm5
    2.7.6-8ubuntu0.6+esm6
    2.7.6-8ubuntu0.6+esm7
    2.7.6-8ubuntu0.6+esm8
    2.7.6-8ubuntu0.6+esm9
    2.7.6-8ubuntu0.6+esm10
    2.7.6-8ubuntu0.6+esm11

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    UBUNTU-CVE-2021-4189 | CVE-DB