What’s Vulnerable › Vulnerabilities

CVE-2020-7773: Cross-site Scripting (XSS)

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2020-11-16 · updated 2026-06-17
• Weakness: CWE-79

Description

This affects the package markdown-it-highlightjs before 3.3.1. It is possible insert malicious JavaScript as a value of lang in the markdown-it-highlightjs Inline code highlighting feature. const markdownItHighlightjs = require("markdown-it-highlightjs"); const md = require('markdown-it'); const reuslt_xss = md() .use(markdownItHighlightjs, { inline: true }) .render('console.log(42){.">js}'); console.log(reuslt_xss);

Affected products

• markdown-it-highlightjs: before 3.3.1 — fixed in 3.3.1

How to fix

Upgrade to a fixed version: markdown-it-highlightjs 3.3.1. Check the vendor advisory for mitigations.

References

• https://github.com/valeriangalliat/markdown-it-highlightjs/blob/v3.3.0/index.js%23L52
• https://github.com/valeriangalliat/markdown-it-highlightjs/pull/14
• https://snyk.io/vuln/SNYK-JS-MARKDOWNITHIGHLIGHTJS-1040461
• https://github.com/valeriangalliat/markdown-it-highlightjs/blob/v3.3.0/index.js%23L52
• https://github.com/valeriangalliat/markdown-it-highlightjs/pull/14
• https://snyk.io/vuln/SNYK-JS-MARKDOWNITHIGHLIGHTJS-1040461

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