Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2021-37533

23
FAUCET Score

CVE-2021-37533 affects Apache Commons Net prior to version 3.9.0, where its FTP client could be redirected by a malicious server to a different host, potentially leaking private network service information. This vulnerability has a CVSS score of 6.5 (Medium), indicating a network-based attack with low complexity, requiring user interaction, and leading to high confidentiality impact. While no active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion has been observed, the vendor has addressed the issue by changing the default behavior in version 3.9.0 to ignore such malicious host redirections.

Impacted Technologies

VendorProductVersion(s)CPE
< 3.9.0CPE matchmatch criteria
cpe:2.3:a:apache:commons_net:*:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
11.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.86%
Probability of exploitation in next 30 days
EPSS Percentile
77.0%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0186 is in the 88th percentile among its peer group of 26,221 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (15)

mavenpatch availablevia ghsa
Product: commons-net:commons-netFixed in: 3.9.0
redhatpatch availablevia redhat_api
Product: RHINT Camel-Q 2.13.3Fixed in: apache-commons-net
View patch
redhatpatch availablevia redhat_api
Product: RHINT Camel-Springboot 3.20.1Fixed in: apache-commons-net
View patch
redhatno patchvia redhat_api
Product: OpenShift Developer Tools and ServicesFixed in: jenkins-2-plugins
redhatno patchvia redhat_api
Product: Red Hat Integration Camel K 1Fixed in: apache-commons-net
redhatno patchvia redhat_api
Product: Red Hat OpenShift Container Platform 4Fixed in: jenkins-2-plugins
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: pki-deps:10.6/apache-commons-net
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: apache-commons-net
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: log4j
redhatend of lifevia redhat_api
Product: Red Hat Software CollectionsFixed in: rh-maven36-apache-commons-net
redhatend of lifevia redhat_api
Product: Migration Toolkit for Applications 6Fixed in: io.netty-netty-tcnative-parent
redhatend of lifevia redhat_api
Product: Migration Toolkit for RuntimesFixed in: io.netty-netty-tcnative-parent
redhatend of lifevia redhat_api
Product: Red Hat Data Grid 8Fixed in: apache-commons-net
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: apache-commons-net
redhatend of lifevia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: log4j:2/log4j

Vendor Advisories (2)

redhatCVE-2021-37533Moderate

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

Feb 15, 2023
mavenGHSA-cgp8-4m63-fhh5medium

Apache Commons Net vulnerable to information leakage via malicious server

Dec 3, 2022

References

lists.apache.org / thread/o6yn9r9x6s94v97264hmgol1sf48mvx7
Issue TrackingMailing ListVendor Advisory
lists.debian.org / debian-lts-announce/2022/12/msg00038.html
Mailing ListThird Party Advisory
debian.org / security/2022/dsa-5307
Third Party Advisory
openwall.com / lists/oss-security/2022/12/03/1
Issue TrackingMailing ListThird Party Advisory