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CVE-2026-65898 high CVSS 7.2

Cross-Site Scripting (XSS) in dompurify (CVE-2026-65898)

Summary

Cross-site scripting in dompurify (CVE-2026-65898). Risk of unauthorized operations or information disclosure. Exploitable via uponSanitizeAttribute. Mitigation: upgrade to 3.4.11 or later.

Original description

The description as published by the source.

Summary

DOMPurify 3.4.7 shipped a security fix ("permanent hook pollution") that makes a registered uponSanitizeAttribute hook's mutation of data.allowedAttributes non-persistent — so allowing an attribute for one element does not leak into later sanitize() calls. The fix clones ALLOWED_ATTR inside _parseConfig.

That guard is silently bypassed whenever the application uses the persistent-config API DOMPurify.setConfig(). setConfig() sets the module flag SET_CONFIG = true, which causes sanitize() to skip _parseConfig entirely — and the clone-guard lives inside _parseConfig. The hook is then handed the live, shared ALLOWED_ATTR object; any data.allowedAttributes[name] = true it writes mutates that shared object permanently, for the lifetime of the DOMPurify instance, across every subsequent call, and across all elements.

If an application uses setConfig() together with an uponSanitizeAttribute hook that conditionally allows a dangerous attribute (onerror, onclick, onmouseover, srcdoc, formaction, …) for "trusted" elements, then one trusted render permanently allows that attribute on untrusted, attacker-controlled content — yielding stored XSS in viewers' browsers. DOMPurify applies no separate /^on/ event-handler blocklist: attribute stripping is governed entirely by the allowlist, so a polluted allowlist is the only gate, and survival in the output is final.

Affected configuration (preconditio…

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-2026-65898 has been found in dompurify.
Attackers can target a specific entry point like uponSanitizeAttribute over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.2/10.
What to do: upgrade dompurify to 3.4.11 or later.
If unsure, ask your IT team or search "dompurify CVE-2026-65898" on the vendor's site.

CVE-2026-65898 (dompurify) — CWE-79 / CVSS v3 7.2
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: uponSanitizeAttribute / data.allowedAttributes / ALLOWED_ATTR / _parseConfig
Patched: 3.4.11 — 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 uponSanitizeAttribute without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of dompurify. Attack surface: uponSanitizeAttribute / data.allowedAttributes / ALLOWED_ATTR / _parseConfig.

🔥 Severity

Severity: High (CVSS 7.2/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 3.4.11.

🛡️ 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 3.4.11

    ステージング環境で 3.4.11 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":"3.4.11"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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