Cross-Site Scripting (XSS) in remark-html (CVE-2021-39199)
Summary
Cross-site scripting in remark-html (CVE-2021-39199). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 13.0.2 or later.
Original description
The description as published by the source.
remark-html is an open source nodejs library which compiles Markdown to HTML. In affected versions the documentation of remark-html has mentioned that it was safe by default. In practice the default was never safe and had to be opted into. That is, user input was not sanitized. This means arbitrary HTML can be passed through leading to potential XSS attacks. The problem has been patched in 13.0.2 and 14.0.1: remark-html is now safe by default, and the implementation matches the documentation. On older affected versions, pass sanitize: true if you cannot update.
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-2021-39199 has been found in remark-html.
Risk of unauthorized operations or information disclosure.
What to do: upgrade remark-html to 13.0.2 or later.
If unsure, ask your IT team or search "remark-html CVE-2021-39199" on the vendor's site.
CVE-2021-39199 (remark-html) — CWE-79
Attack vector: remote (network-reachable) / unauthenticated
Patched: 13.0.2 — 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 remark-html.
Check the vendor advisory for the affected versions of remark-html.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 13.0.2.
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 'remark-html' . 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
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1Identify exposure identify
grep -r 'remark-html' . | 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
remark-html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 remark-html to 13.0.2ステージング環境で 13.0.2 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
- advisory npmjs.com
- package github.com
- patch github.com
- patch github.com
- patch github.com