Freeform Craft Plugin CP UI (builder/integrations) has Stored Cross-Site Scripting (XSS) issue

Summary An authenticated, low-privilege user (able to create/edit forms) can inject arbitrary HTML/JS into the Craft Control Panel (CP) builder and integrations views. User-controlled form labels and integration metadata are rendered with dangerouslySetInnerHTML without sanitization, leading to stored XSS that executes when any admin views the builder/integration screens.

Affected Product

• Ecosystem: Packagist (Craft CMS plugin)
• Package: solspace/craft-freeform
• Version: <= 5.14.6 (latest observed). Likely all 5.x until patched.

Details

• Root cause: Multiple user-controlled strings (field labels, section labels, integration icons, short names, WYSIWYG previews) are injected into React components using dangerouslySetInnerHTML without sanitization.
• Evidence: dangerouslySetInnerHTML on user-controlled properties in bundled CP JS at packages/plugin/src/Resources/js/client/client.js.

PoCs

• Label-based XSS:
  1. In Craft CP, create/edit a Freeform field and set its label to <img src=x onerror="alert('xss-label')">.
  2. Open the form builder view containing the field.
  3. Alert executes (stored XSS).
• Integration icon SVG:
  1. Set an integration "icon SVG" to <svg><script>alert('xss-icon')</script></svg>.
  2. Open the integrations CP view.
  3. Script executes.

Impact Arbitrary JS in admin CP; session/CSRF token theft; potential full admin takeover via DOM-driven actions.

Remediation

• Sanitize/HTML-encode all user-controlled strings before passing to dangerouslySetInnerHTML, or avoid it for labels/titles/icons.
• Server-side: strip/escape disallowed tags on save for fields, integration metadata, WYSIWYG content.
• Add regression tests with <img onerror> payloads to ensure no execution in builder/integration views.

Workarounds

• Restrict form-edit permissions to trusted admins only until patched.
• Consider CSP that disallows inline scripts (defense-in-depth only).

Credits

• Discovered by https://www.linkedin.com/in/praveenkavinda/ | Prav33N-Sec.