CVE-2026-47423: Dompurify Cross-Site Scripting Vulnerability

HIGH
Advisory Identifier: GHSA-87xg-pxx2-7hvx
Share
CVSS 8.2
CWE-79
Published
Advisory Summary

CVE-2026-47423 is a HIGH (CVSS 8.2) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Dompurify libraries in the npm ecosystem. The issue involves dompurify xss via selectedcontent re-clone. Remediation is available by upgrading affected packages to version 3.4.5.

CVE-2026-47423 at a Glance

CVE Identifier CVE-2026-47423
GHSA Identifier GHSA-87xg-pxx2-7hvx
Severity HIGH
CVSS v3.1 Base Score 8.2
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Dompurify
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 8.2

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2026-47423

To remediate this vulnerability, upgrade all affected Dompurify dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

dompurify fixed: 3.4.5 
npm install dompurify@3.4.5
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls dompurify

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-47423, inspect your project dependencies using npm:

npm ls dompurify

Analyze the terminal output to locate any version of Dompurify in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 3.4.5), your application is affected.

Note: The npm ls dompurify command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Dompurify, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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 `<selectedcontent>` clone from the selected `<option>` 2. DOMPurify walks and sanitizes that generated clone. 3. DOMPurify reaches the original `<option>` and removes `selected=javascript:1` 4. The browser refreshes the `<selectedcontent>` 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 `<selectedcontent>`. ### PoC ```js const dirty = '<select><button><selectedcontent></selectedcontent></button>' + '<option selected=javascript:1>' + '<img src=x onerror=alert(1)>x' + '</option></select>'; const clean = DOMPurify.sanitize(dirty); console.log(clean); document.body.innerHTML = clean; ``` Observed "sanitized" output in Chromium 148/WebKit 625: ```html <select><button><selectedcontent><img src="x" onerror="alert(1)">x</selectedcontent></button><option><img src="x">x</option></select> ``` After reinsertion, the browser updates the live DOM and strips the handler from the displayed clone, but the `onerror` has already fired: ```html <select><button><selectedcontent><img src="x">x</selectedcontent></button><option><img src="x">x</option></select> ``` Reproduced in Chromium and WebKit, but not Safari (not yet latest WebKit) or Firefox. Will likely change with [browser support](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/selectedcontent) 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 then insert the returned string into the page, for example with innerHTML.

CVE-2026-47423 Affected Dompurify Versions

1 component(s)
Fixed Versions:
3.4.5
Product / Package Ecosystem Affected Versions Fixed Version
dompurify
npm/dompurify
npm
≥ 3.4.4
< 3.4.5
All 1 versions
3.4.4
3.4.5

References

GitHub Advisory / Wiki ADVISORY
https://github.com/cure53/DOMPurify/security/advisories/GHSA-87xg-pxx2-7hvx
Dompurify Source Repository REPOSITORY
https://github.com/cure53/DOMPurify

Frequently Asked Questions

What is CVE-2026-47423?
CVE-2026-47423 is a security vulnerability in Dompurify involving DOMPurify XSS via selectedcontent re-clone under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Dompurify versions are affected?
Affected versions include releases prior to 3.4.5 across affected packages: dompurify.
What version fixes CVE-2026-47423?
Upgrading to 3.4.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is dompurify affected?
Yes, dompurify is affected in releases prior to 3.4.5. Upgrade your dependency to 3.4.5 or later.
What is the CVSS score of CVE-2026-47423?
CVE-2026-47423 has a CVSS v3.1 base score of 8.2 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N.
What CWE is associated with CVE-2026-47423?
CVE-2026-47423 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check npm dependencies for CVE-2026-47423?
Run the dependency tree command: 'npm ls dompurify'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-87xg-pxx2-7hvx",
  "modified" : "2026-06-01T14:07:29Z",
  "published" : "2026-06-01T14:07:29Z",
  "aliases" : [ "CVE-2026-47423" ],
  "summary" : "DOMPurify XSS via selectedcontent re-clone",
  "details" : "### Summary\nDOMPurify 3.4.4 allows `selectedcontent` by default, allowing a chain in which browsers \"re-clone\" an XSS payload after sanitization, effectively bypassing DOMPurify. \n\n### Details\nThe chain is as follows:\n1. The browser parses the input and creates a `<selectedcontent>` clone from the selected `<option>`\n2. DOMPurify walks and sanitizes that generated clone.\n3. DOMPurify reaches the original `<option>` and removes `selected=javascript:1`\n4. The browser refreshes the `<selectedcontent>` clone from the original `option`'s content.\n5. The refreshed clone is in a subtree DOMPurify already walked, which DOMPurify doesn't go back to sanitize\n6. The returned string contains unsanitized markup inside `<selectedcontent>`.\n\n### PoC\n```js\nconst dirty =\n  '<select><button><selectedcontent></selectedcontent></button>' +\n  '<option selected=javascript:1>' +\n  '<img src=x onerror=alert(1)>x' +\n  '</option></select>';\n\nconst clean = DOMPurify.sanitize(dirty);\nconsole.log(clean);\n\ndocument.body.innerHTML = clean;\n```\n\nObserved \"sanitized\" output in Chromium 148/WebKit 625:\n```html\n<select><button><selectedcontent><img src=\"x\" onerror=\"alert(1)\">x</selectedcontent></button><option><img src=\"x\">x</option></select>\n```\n\nAfter reinsertion, the browser updates the live DOM and strips the handler from the displayed clone, but the `onerror` has already fired:\n```html\n<select><button><selectedcontent><img src=\"x\">x</selectedcontent></button><option><img src=\"x\">x</option></select>\n```\n\nReproduced in Chromium and WebKit, but not Safari (not yet latest WebKit) or Firefox. Will likely change with [browser support](https://developer.mozilla.org/en-US/docs/Web/HTML/Reference/Elements/selectedcontent) for `selectedcontent`.\n\n### Impact\nThis is a default-configuration DOMPurify sanitizer bypass resulting in XSS.\n\nApplications are impacted if they sanitize attacker-controlled HTML with DOMPurify 3.4.4 using the string-input path and then insert the returned string into the page, for example with innerHTML.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "dompurify"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "3.4.4"
      }, {
        "fixed" : "3.4.5"
      } ]
    } ],
    "versions" : [ "3.4.4" ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/cure53/DOMPurify/security/advisories/GHSA-87xg-pxx2-7hvx"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/cure53/DOMPurify"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-01T14:07:29Z",
    "nvd_published_at" : null
  }
}