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Fencer Intel
medium 6.5

CVE-2021-37533 json

Apache Commons Net's FTP client trusts the host from PASV response by default

published 3y ago modified last mo. also GHSA-cgp8-4m63-fhh5 , EUVD-2022-7599

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.2%
EPSS 2.2% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

Prior to Apache Commons Net 3.9.0, Net's FTP client trusts the host from PASV response by default. A malicious server can redirect the Commons Net code to use a different host, but the user has to connect to the malicious server in the first place. This may lead to leakage of information about services running on the private network of the client. The default in version 3.9.0 is now false to ignore such hosts, as cURL does. See https://issues.apache.org/jira/browse/NET-711.

Patch / fix

  • maven commons-net:commons-net 3.9.0
  • Apache Software Foundation Apache Commons Net 3.9.0
  • libcommons-net-java Debian 14, Debian 13, Debian 12 3.9.0-1

debian advisories DEBIAN-CVE-2021-37533

  • libcommons-net-java Ubuntu 18.04 LTS 3.6-1+deb11u1build0.18.04.1
  • libcommons-net-java Ubuntu 20.04 LTS 3.6-1+deb11u1build0.20.04.1
  • libcommons-net-java Ubuntu 22.04 LTS 3.6-1+deb11u1build0.22.04.1
  • libcommons-net-java Ubuntu Pro 16.04 LTS 3.4-2ubuntu2+esm1

ubuntu advisories UBUNTU-CVE-2021-37533

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • apache-commons-net openSUSE Tumbleweed 3.9.0-1.1

opensuse advisories openSUSE-SU-2024:12549-1

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-37533 updated cvss 6.5

apache-commons-net: FTP client trusts the host from PASV response by default

  • Red Hat Migration Toolkit for Applications 6 io.netty-netty-tcnative-parent Red Hat Migration Toolkit for Runtimes io.netty-netty-tcnative-parent
    affected: no fix planned “Will not fix”
  • Red Hat OpenShift Developer Tools and Services jenkins-2-plugins
    affected: no fix available
  • Red Hat Data Grid 8 apache-commons-net Red Hat Enterprise Linux 7 apache-commons-net, apache-commons-net-javadoc Red Hat Enterprise Linux 8 log4j, log4j-jcl, log4j-web, log4j-slf4j, apache-commons-net, apache-commons-net-javadoc Red Hat Enterprise Linux 9 log4j, log4j-jcl, log4j-slf4j, apache-commons-net
    affected: no fix planned “Will not fix”
  • Red Hat Fuse 7 apache-commons-net
    affected: no fix planned “Out of support scope”
  • Red Hat Integration Camel K 1 apache-commons-net Red Hat Integration Camel Quarkus 1 apache-commons-net
    affected: no fix available
  • Red Hat JBoss Data Grid 7 apache-commons-net Red Hat JBoss Enterprise Application Platform 6 apache-commons-net Red Hat JBoss Fuse 6 apache-commons-net Red Hat JBoss Fuse Service Works 6 apache-commons-net
    affected: no fix planned “Out of support scope”
  • Red Hat OpenShift Container Platform 4 jenkins-2-plugins
    affected: no fix available
  • Red Hat OpenStack Platform 13 (Queens) opendaylight Red Hat Single Sign-On 7 apache-commons-net
    affected: no fix planned “Out of support scope”
show 4 more
  • Red Hat Software Collections rh-maven36-apache-commons-net, rh-maven36-apache-commons-net-javadoc
    affected: no fix planned “Will not fix”
  • Red Hat RHINT Camel-Q 2.13.3
    fixed: vendor fix RHSA-2023:3667
  • Red Hat RHINT Camel-Springboot 3.20.1
    fixed: vendor fix RHSA-2023:2100
  • Red Hat A-MQ Clients 2 apache-commons-net Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/elasticsearch6-rhel8 Red Hat Migration Toolkit for Applications 6 org.jboss.windup-windup-parent Red Hat Migration Toolkit for Runtimes org.jboss.windup-windup-parent Red Hat Decision Manager 7 apache-commons-net Red Hat JBoss Enterprise Application Platform 7 apache-commons-net
    +2 more products
    Red Hat JBoss Enterprise Application Platform Expansion Pack apache-commons-net Red Hat Process Automation 7 apache-commons-net
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

2.17% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
NVD 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
maven commons-net:commons-net
<3.9.0
3.9.0

Affected products

  • Apache Software Foundation Apache Commons Net

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.