Craft CMS Vulnerable to Stored XSS in Number Prefix & Suffix Fields
Impact
A stored XSS vulnerability exists in the Number field type settings. The Prefix and Suffix fields are rendered using the |md|raw Twig filter without proper escaping, allowing script execution when the Number field is displayed on users' profiles.
Source excerpt · OSVAffected packages
Start with the recorded fix for your release branch. Check your installed version and test compatibility before upgrading. Fixing this advisory does not rule out other vulnerabilities in the release.
| Affected range | Recorded fix |
|---|---|
| From 5.0.0-RC1 before 5.8.22Ecosystem versions | 5.8.22 |
| From 4.0.0-RC1 before 4.16.18Ecosystem versions | 4.16.18 |
Version evidence: OSV · GHSA-9f5h-mmq6-2x78
View original version evidence (370 explicit versions)
Original source description
Summary
A stored XSS vulnerability exists in the Number field type settings. The Prefix and Suffix fields are rendered using the |md|raw Twig filter without proper escaping, allowing script execution when the Number field is displayed on users' profiles.
Proof of Concept
Required Permissions
- Administrator access
allowAdminChangesis enabled in production, which is against our security recommendations.
Steps to Reproduce
- Log in with an admin account
- Navigate to Settings → Fields → New field
- Choose Number as the field type
- Set the Prefix/Suffix Text field to: <img width="611" height="908" alt="image" src="https://github.com/user-attachments/assets/63766ca4-4fa9-490b-8bea-37364137527d" />
<img src=x onerror="alert('Number Prefix/Suffix XSS')" hidden>
- Save the field
- Add this field to any element (e.g., User Profile fields via Settings → Users → User Fields)
- Navigate to your account (
/admin/myaccount) or any user profile (/admin/users/{id}) - XSS executes when viewing the form <img width="1246" height="677" alt="image-1" src="https://github.com/user-attachments/assets/dafeb2b7-905f-4a4b-b3d6-1c16a905498f" />
Mitigation
Sanitize prefix/suffix before rendering or use |e filter instead of |raw.
References
- Security advisory github.com/craftcms/cms/security/advisories/GHSA-9f5h-mmq6-2x78
- Security advisory nvd.nist.gov/vuln/detail/CVE-2026-25496
- Patch github.com/craftcms/cms/commit/cb5fb0e979e72f315c9178fc031883d49527f513
- Source reference github.com/craftcms/cms
- Release notes github.com/craftcms/cms/releases/tag/4.16.18
- Release notes github.com/craftcms/cms/releases/tag/5.8.22