CVE-2021-4189

NameCVE-2021-4189
DescriptionA 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
ReferencesDLA-2919-1, DLA-3432-1, DLA-3477-1, ELA-572-1, ELA-598-1, ELA-884-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
pypy (PTS)jessie2.4.0+dfsg-3vulnerable
stretch5.6.0+dfsg-4vulnerable
buster7.0.0+dfsg-3vulnerable
bullseye7.3.3+dfsg-2vulnerable
pypy3 (PTS)buster7.0.0+dfsg-3vulnerable
bullseye7.3.5+dfsg-2+deb11u2vulnerable
bullseye (security)7.3.5+dfsg-2+deb11u3vulnerable
bookworm7.3.11+dfsg-2+deb12u2fixed
sid, trixie7.3.17+dfsg-2fixed
python2.7 (PTS)jessie, jessie (lts)2.7.9-2-ds1-1+deb8u12fixed
stretch (security)2.7.13-2+deb9u6fixed
stretch (lts), stretch2.7.13-2+deb9u9fixed
buster (security), buster, buster (lts)2.7.16-2+deb10u4fixed
bullseye2.7.18-8+deb11u1vulnerable
python3.4 (PTS)jessie, jessie (lts)3.4.2-1+deb8u18fixed
python3.5 (PTS)stretch (security)3.5.3-1+deb9u5vulnerable
stretch (lts), stretch3.5.3-1+deb9u10fixed
python3.7 (PTS)buster, buster (lts)3.7.3-2+deb10u8fixed
buster (security)3.7.3-2+deb10u7fixed
python3.9 (PTS)bullseye3.9.2-1vulnerable

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
pypysourcejessie(unfixed)end-of-life
pypysource(unstable)(unfixed)
pypy3source(unstable)7.3.8+dfsg-1
python2.7sourceexperimental2.7.18-13.1~exp1
python2.7sourcejessie2.7.9-2-ds1-1+deb8u9ELA-598-1
python2.7sourcestretch2.7.13-2+deb9u6DLA-2919-1
python2.7sourcebuster2.7.16-2+deb10u2DLA-3432-1
python2.7source(unstable)2.7.18-13.1
python3.10source(unstable)(not affected)
python3.4sourcejessie3.4.2-1+deb8u12ELA-572-1
python3.4source(unstable)(unfixed)
python3.5sourcestretch3.5.3-1+deb9u7ELA-884-1
python3.5source(unstable)(unfixed)
python3.7sourcebuster3.7.3-2+deb10u5DLA-3477-1
python3.7source(unstable)(unfixed)
python3.9source(unstable)3.9.7-1

Notes

- python3.10 <not-affected> (Fixed before initial upload to Debian unstable)
[bullseye] - python3.9 <no-dsa> (Minor issue)
[stretch] - python3.5 <no-dsa> (Minor issue)
[bullseye] - python2.7 <ignored> (Python 2.7 in Bullseye not covered by security support)
[bullseye] - pypy3 <no-dsa> (Minor issue)
[buster] - pypy3 <no-dsa> (Minor issue)
https://bugs.python.org/issue43285
https://github.com/python/cpython/commit/0ab152c6b5d95caa2dc1a30fa96e10258b5f188e (master)
https://github.com/python/cpython/commit/7dcb4baa4f0fde3aef5122a8e9f6a41853ec9335 (v3.9.3)
https://github.com/python/cpython/commit/79373951b3eab585d42e0f0ab83718cbe1d0ee33 (v3.7.11)
https://github.com/python/cpython/commit/4134f154ae2f621f25c5d698cc0f1748035a1b88 (v3.6.14)
https://bugzilla.redhat.com/show_bug.cgi?id=2036020

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