CVE-2020-7642: Lazysizes Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-hg2p-2cvq-4ppv
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CVSS 5.4
CWE-79
Published
Advisory Summary

CVE-2020-7642 is a MODERATE (CVSS 5.4) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Lazysizes libraries in the npm ecosystem. The issue involves cross-site scripting in lazysizes. Remediation is available by upgrading affected packages to version 5.2.1.

CVE-2020-7642 at a Glance

CVE Identifier CVE-2020-7642
GHSA Identifier GHSA-hg2p-2cvq-4ppv
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Lazysizes
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.4

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

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

How to Fix CVE-2020-7642

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

lazysizes fixed: 5.2.1 
npm install lazysizes@5.2.1
Verify Direct and Transitive Dependencies

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

npm ls lazysizes

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2020-7642, inspect your project dependencies using npm:

npm ls lazysizes

Analyze the terminal output to locate any version of Lazysizes in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.2.1), your application is affected.

Note: The npm ls lazysizes command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Lazysizes, 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

lazysizes through 5.2.0 allows execution of malicious JavaScript. The following attributes are not sanitized by the video-embed plugin: `data-vimeo`, `data-vimeoparams`, `data-youtube` and `data-ytparams` which can be abused to inject malicious JavaScript.

CVE-2020-7642 Affected Lazysizes Versions

1 component(s)
Fixed Versions:
5.2.1
Product / Package Ecosystem Affected Versions Fixed Version
lazysizes
npm/lazysizes
npm
< 5.2.1
5.2.1

References

NVD — CVE-2020-7642 NVD
https://nvd.nist.gov/vuln/detail/CVE-2020-7642
Security Fix Commit FIX COMMIT
https://github.com/aFarkas/lazysizes/commit/3720ab8262552d4e063a38d8492f9490a231fd48
snyk.io/vuln/snyk-js-lazysi... WEB
https://snyk.io/vuln/SNYK-JS-LAZYSIZES-567144

Frequently Asked Questions

What is CVE-2020-7642?
CVE-2020-7642 is a security vulnerability in Lazysizes involving Cross-site scripting in lazysizes under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Lazysizes versions are affected?
Affected versions include releases prior to 5.2.1 across affected packages: lazysizes.
What version fixes CVE-2020-7642?
Upgrading to 5.2.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is lazysizes affected?
Yes, lazysizes is affected in releases prior to 5.2.1. Upgrade your dependency to 5.2.1 or later.
What is the CVSS score of CVE-2020-7642?
CVE-2020-7642 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2020-7642?
CVE-2020-7642 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check npm dependencies for CVE-2020-7642?
Run the dependency tree command: 'npm ls lazysizes'. 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-hg2p-2cvq-4ppv",
  "modified" : "2023-09-05T22:42:28Z",
  "published" : "2021-12-10T20:06:23Z",
  "aliases" : [ "CVE-2020-7642" ],
  "summary" : "Cross-site scripting in lazysizes",
  "details" : "lazysizes through 5.2.0 allows execution of malicious JavaScript. The following attributes are not sanitized by the video-embed plugin: `data-vimeo`, `data-vimeoparams`, `data-youtube` and `data-ytparams` which can be abused to inject malicious JavaScript.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "lazysizes"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.2.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 5.2.0"
    }
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2020-7642"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aFarkas/lazysizes/commit/3720ab8262552d4e063a38d8492f9490a231fd48"
  }, {
    "type" : "WEB",
    "url" : "https://snyk.io/vuln/SNYK-JS-LAZYSIZES-567144"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-05-25T20:08:07Z",
    "nvd_published_at" : "2020-04-22T16:15:00Z"
  }
}