CVE-2021-37533: Commons net Apache Commons Net Vulnerable To Vulnerability

MODERATE
Advisory Identifier: GHSA-cgp8-4m63-fhh5
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CVSS 6.5
CWE-20
Published
Advisory Summary

CVE-2021-37533 is a MODERATE (CVSS 6.5) apache commons net vulnerable to vulnerability (CWE-20: Improper Input Validation) affecting Commons net libraries in the Maven ecosystem. The issue involves apache commons net vulnerable to information leakage via malicious server. Remediation is available by upgrading affected packages to version 3.9.0.

CVE-2021-37533 at a Glance

CVE Identifier CVE-2021-37533
GHSA Identifier GHSA-cgp8-4m63-fhh5
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-20: Improper Input Validation
Affected Product Commons net
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity None (I:N)
Availability None (A:N)

How to Fix CVE-2021-37533

To remediate this vulnerability, upgrade all affected Commons net dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

commons-net:commons-net fixed: 3.9.0 
<dependency>
    <groupId>commons-net</groupId>
    <artifactId>commons-net</artifactId>
    <version>3.9.0</version>
</dependency>
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree -Dincludes=commons-net

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2021-37533, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree -Dincludes=commons-net

Analyze the terminal output to locate any version of Commons net in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.9.0), your application is affected.

Note: The mvn dependency:tree -Dincludes=commons-net command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-20: Improper Input Validation, where the product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. In Commons net, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

CVE-2021-37533 Affected Commons net Versions

1 component(s)
Fixed Versions:
3.9.0
Product / Package Ecosystem Affected Versions Fixed Version
commons-net:commons-net
maven/commons-net/commons-net
Maven
< 3.9.0
3.9.0

References

NVD — CVE-2021-37533 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-37533
Security Fix Commit FIX COMMIT
https://github.com/apache/commons-net/commit/4fe1bae56e53f32756b1ca3296f3dd2c45e3e060
Commons net Source Repository REPOSITORY
https://github.com/apache/commons-net
issues.apache.org/jira/browse/net-711 WEB
https://issues.apache.org/jira/browse/NET-711
lists.apache.org/thread/o6yn9r9x6s94... WEB
https://lists.apache.org/thread/o6yn9r9x6s94v97264hmgol1sf48mvx7
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2022/12/msg00038.html
Commons net Security Information SECURITY
https://www.debian.org/security/2022/dsa-5307
Commons net Security Information SECURITY
http://www.openwall.com/lists/oss-security/2022/12/03/1

Frequently Asked Questions

What is CVE-2021-37533?
CVE-2021-37533 is a security vulnerability in Commons net involving Apache Commons Net vulnerable to information leakage via malicious server under CWE-20: Improper Input Validation.
Which Commons net versions are affected?
Affected versions include releases prior to 3.9.0 across affected packages: commons-net:commons-net.
What version fixes CVE-2021-37533?
Upgrading to 3.9.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is commons-net affected?
Yes, commons-net:commons-net is affected in releases prior to 3.9.0. Upgrade your dependency to 3.9.0 or later.
What is the CVSS score of CVE-2021-37533?
CVE-2021-37533 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N.
What CWE is associated with CVE-2021-37533?
CVE-2021-37533 is classified under CWE-20: Improper Input Validation (The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.).
How can I check Maven dependencies for CVE-2021-37533?
Run the dependency tree command: 'mvn dependency:tree -Dincludes=commons-net'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-cgp8-4m63-fhh5",
  "modified" : "2022-12-06T16:19:45Z",
  "published" : "2022-12-03T15:30:26Z",
  "aliases" : [ "CVE-2021-37533" ],
  "summary" : "Apache Commons Net vulnerable to information leakage via malicious server",
  "details" : "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.\nThe 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.\n",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Maven",
      "name" : "commons-net:commons-net"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.9.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-37533"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/apache/commons-net/commit/4fe1bae56e53f32756b1ca3296f3dd2c45e3e060"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/apache/commons-net"
  }, {
    "type" : "WEB",
    "url" : "https://issues.apache.org/jira/browse/NET-711"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread/o6yn9r9x6s94v97264hmgol1sf48mvx7"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2022/12/msg00038.html"
  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2022/dsa-5307"
  }, {
    "type" : "WEB",
    "url" : "http://www.openwall.com/lists/oss-security/2022/12/03/1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-20" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2022-12-05T23:21:08Z",
    "nvd_published_at" : "2022-12-03T15:15:00Z"
  }
}