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CVE-2026-47423 high CVSS 8.2

Cross-Site Scripting (XSS) in dompurify (CVE-2026-47423)

Summary

Cross-site scripting in dompurify (CVE-2026-47423). Confidential information can be exposed externally. Exploitable via selectedcontent. Mitigation: upgrade to 3.4.5 or later.

Original description

The description as published by the source.

Summary

DOMPurify 3.4.4 allows selectedcontent by default, allowing a chain in which browsers "re-clone" an XSS payload after sanitization, effectively bypassing DOMPurify.

Details

The chain is as follows:

  1. The browser parses the input and creates a clone from the selected
  2. DOMPurify walks and sanitizes that generated clone.
  3. DOMPurify reaches the original `` and removes selected=javascript:1
  4. The browser refreshes the `` clone from the original option's content.
  5. The refreshed clone is in a subtree DOMPurify already walked, which DOMPurify doesn't go back to sanitize
  6. The returned string contains unsanitized markup inside ``.

PoC

const dirty =
  '' +
  '' +
  'x' +
  '';

const clean = DOMPurify.sanitize(dirty);
console.log(clean);

document.body.innerHTML = clean;

Observed "sanitized" output in Chromium 148/WebKit 625:

xx

After reinsertion, the browser updates the live DOM and strips the handler from the displayed clone, but the onerror has already fired:

xx

Reproduced in Chromium and WebKit, but not Safari (not yet latest WebKit) or Firefox. Will likely change with browser support for selectedcontent.

Impact

This is a default-configuration DOMPurify sanitizer bypass resulting in XSS.

Applications are impacted if they sanitize attacker-controlled HTML with DOMPurify 3.4.4 using the string-input path and…

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-2026-47423 has been found in dompurify.
Attackers can target a specific entry point like selectedcontent over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.2/10.
What to do: upgrade dompurify to 3.4.5 or later.
If unsure, ask your IT team or search "dompurify CVE-2026-47423" on the vendor's site.

CVE-2026-47423 (dompurify) — CWE-79 / CVSS v3 8.2
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: selectedcontent / option / onerror
Patched: 3.4.5 — 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 selectedcontent without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of dompurify. Attack surface: selectedcontent / option / onerror.

🔥 Severity

Severity: High (CVSS 8.2/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 3.4.5.

🛡️ 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 3.4.5

    ステージング環境で 3.4.5 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":"SEMVER","events":[{"introduced":"3.4.4"},{"fixed":"3.4.5"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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