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CVE-2026-65900 medium CVSS 6.1

Cross-Site Scripting (XSS) in dompurify (CVE-2026-65900)

Summary

Cross-site scripting in dompurify (CVE-2026-65900). Risk of unauthorized operations or information disclosure. Exploitable via SAFE_FOR_TEMPLATES. Mitigation: upgrade to 3.4.8 or later.

Original description

The description as published by the source.

Summary

When DOMPurify is configured with both SAFE_FOR_TEMPLATES: true and RETURN_DOM: true (or IN_PLACE: true), an attacker can inject template expressions, such as ${evil}, {{evil}}, or <%evil%>, that survive the sanitization pass inside `` element content. This bypasses the explicit purpose of SAFE_FOR_TEMPLATES, which is to prevent template engine evaluation of user-supplied content.

Note: The string output path is not affected. Only the DOM return paths (RETURN_DOM: true, RETURN_DOM_FRAGMENT: true, IN_PLACE: true) are vulnerable.

Description

Background

SAFE_FOR_TEMPLATES is designed to strip {{ }}, ${ }, and <% %> expressions from sanitized output so that downstream template engines do not evaluate user-controlled content. The feature operates through two mechanisms:

  1. Per-node scrubbing (_sanitizeElements, src/purify.ts:1403), scrubs individual text nodes during the main sanitization walk.
  2. Final normalization pass (_scrubTemplateExpressions, src/purify.ts:1115), calls node.normalize() to merge adjacent text nodes, then walks the merged nodes and strips any expressions that only appeared after merging.

The Gap

_scrubTemplateExpressions uses a standard NodeIterator rooted at the output body:

// src/purify.ts:1117
const walker = createNodeIterator.call(
  node.ownerDocument || node,
  node,
  NodeFilter.SHOW_TEXT | NodeFilter.SHOW_COMMENT | ...,
  null
);

Per the DOM spe…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

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-2026-65900 has been found in dompurify.
Attackers can target a specific entry point like SAFE_FOR_TEMPLATES over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.1/10.
What to do: upgrade dompurify to 3.4.8 or later.
If unsure, ask your IT team or search "dompurify CVE-2026-65900" on the vendor's site.

CVE-2026-65900 (dompurify) — CWE-79 / CVSS v3 6.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: SAFE_FOR_TEMPLATES / _sanitizeElements / _scrubTemplateExpressions / NodeIterator
Patched: 3.4.8 — 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.

❓ What is the problem

Cross-site scripting (XSS) (CWE-79) exists in dompurify. Attackers reach the vulnerable code path via SAFE_FOR_TEMPLATES without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of dompurify. Attack surface: SAFE_FOR_TEMPLATES / _sanitizeElements / _scrubTemplateExpressions / NodeIterator.

🔥 Severity

Severity: Medium (CVSS 6.1/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 3.4.8.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'dompurify' . 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

  1. 1
    Identify exposure identify 
    grep -r 'dompurify' . | 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 dompurify を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade dompurify to 3.4.8

    ステージング環境で 3.4.8 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。

  3. 3
    Post-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

npm dompurify
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.4.8"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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