CVE-2021-20153: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-xqh9-rp73-qqh5
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CWE-59
Published
Advisory Summary

CVE-2021-20153 is a MODERATE security vulnerability vulnerability (CWE-59: Improper Link Resolution Before File Access ('Link Following')) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.. Remediation is available in the latest vendor maintenance releases.

CVE-2021-20153 at a Glance

CVE Identifier CVE-2021-20153
GHSA Identifier GHSA-xqh9-rp73-qqh5
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-59: Improper Link Resolution Before File Access ('Link Following')
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

How to Fix CVE-2021-20153

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

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

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2021-20153, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

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

Note: The mvn dependency:tree 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-59: Improper Link Resolution Before File Access ('Link Following'), where the product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource. In Software, 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

Trendnet AC2600 TEW-827DRU version 2.08B01 contains a symlink vulnerability in the bittorrent functionality. If enabled, the bittorrent functionality is vulnerable to a symlink attack that could lead to remote code execution on the device. If an end user inserts a flash drive with a malicious symlink on it that the bittorrent client can write downloads to, then a user is able to download arbitrary files to any desired location on the devices filesystem, which could lead to remote code execution. Example directories vulnerable to this include "config", "downloads", and "torrents", though it should be noted that "downloads" is the only vector that allows for arbitrary files to be downloaded to arbitrary locations.

References

NVD — CVE-2021-20153 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-20153
Software Security Information SECURITY
https://www.tenable.com/security/research/tra-2021-54

Frequently Asked Questions

What is CVE-2021-20153?
CVE-2021-20153 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-59: Improper Link Resolution Before File Access ('Link Following').
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2021-20153?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What CWE is associated with CVE-2021-20153?
CVE-2021-20153 is classified under CWE-59: Improper Link Resolution Before File Access ('Link Following') (The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.).
How can I check Maven dependencies for CVE-2021-20153?
Run the dependency tree command: 'mvn dependency:tree'. 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-xqh9-rp73-qqh5",
  "modified" : "2022-01-08T00:00:38Z",
  "published" : "2021-12-31T00:00:34Z",
  "aliases" : [ "CVE-2021-20153" ],
  "details" : "Trendnet AC2600 TEW-827DRU version 2.08B01 contains a symlink vulnerability in the bittorrent functionality. If enabled, the bittorrent functionality is vulnerable to a symlink attack that could lead to remote code execution on the device. If an end user inserts a flash drive with a malicious symlink on it that the bittorrent client can write downloads to, then a user is able to download arbitrary files to any desired location on the devices filesystem, which could lead to remote code execution. Example directories vulnerable to this include \"config\", \"downloads\", and \"torrents\", though it should be noted that \"downloads\" is the only vector that allows for arbitrary files to be downloaded to arbitrary locations.",
  "severity" : [ ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-20153"
  }, {
    "type" : "WEB",
    "url" : "https://www.tenable.com/security/research/tra-2021-54"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-59" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2021-12-30T22:15:00Z"
  }
}