Cross-Site Scripting (XSS) in markdown-it-highlightjs (CVE-2020-7773)
Summary
Cross-site scripting in markdown-it-highlightjs (CVE-2020-7773). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 3.3.1 or later.
Original description
The description as published by the source.
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);
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2020-7773 has been found in markdown-it-highlightjs.
Risk of unauthorized operations or information disclosure.
What to do: upgrade markdown-it-highlightjs to 3.3.1 or later.
If unsure, ask your IT team or search "markdown-it-highlightjs CVE-2020-7773" on the vendor's site.
CVE-2020-7773 (markdown-it-highlightjs) — CWE-79
Attack vector: remote (network-reachable) / unauthenticated
Patched: 3.3.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Cross-site scripting (XSS) (CWE-79) exists in markdown-it-highlightjs.
Check the vendor advisory for the affected versions of markdown-it-highlightjs.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 3.3.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'markdown-it-highlightjs' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'markdown-it-highlightjs' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
markdown-it-highlightjsを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade markdown-it-highlightjs to 3.3.1ステージング環境で 3.3.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- web github.com
- web github.com
- web snyk.io