rhukster/dom-sanitizer: SVG tag allows CSS injection via unfiltered url() and @import directives

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

4.7 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:N/A:N

EPSS

• CVE-2026-40301: 0.32% estimated exploitation activity in the next 30 days; percentile 25.26 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary DOMSanitizer::sanitize() allows <style elements in SVG content but never inspects their text content. CSS url() references and @import rules pass through unfiltered, causing the browser to issue HTTP requests to attacker-controlled hosts when the sanitized SVG is rendered. Details In src/DOMSanitizer.php, 'style' is listed in the SVG allowed-tag array (line 31). The sanitize() method (lines 111–133) removes disallowed tags and strips attributes matching the EXTERNALURL pattern — but text node content of <style elements is never examined. Because CSS rules live in text nodes, EXTERNALURL filtering never applies to them. Vulnerable code (src/DOMSanitizer.php, line 31): The following payload survives sanitize() intact: PoC Render the returned string in a browser. The browser sends a GET request to https://attacker.example/collect. Impact Any application that passes user-controlled SVG through DOMSanitizer::sanitize() and renders the output in a browser is vulnerable. An attacker…

Published by the source

10 Apr 2026, 21:08 UTC

Last modified by the source

24 Apr 2026, 20:48 UTC

Source last checked

26 Oct 2026, 14:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-93vf-569f-22cq

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-40301

Advisory: rhukster/dom-sanitizer: SVG tag allows CSS injection via unfiltered url() and @import directives
IDs: CVE-2026-40301, GHSA-93vf-569f-22cq
Record: https://patchnext.com/advisories/cve-2026-40301 (revision 1, source checked 26 Oct 2026, 14:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: rhukster/dom-sanitizer 1.0.10. A vendor fix does not mean a deployment is fixed.

## Affected components
- Packagist rhukster/dom-sanitizer: affected < 1.0.10; fixed in 1.0.10

## Suggested inspection (read-only)
- Packagist rhukster/dom-sanitizer: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on rhukster/dom-sanitizer.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-93vf-569f-22cq (GitHub-reviewed advisory GHSA-93vf-569f-22cq lists affected ranges: Packagist rhukster/dom-sanitizer >=0 <1.0.10)

Commands are suggestions: review each one before running it.