Moderate severityNVD Advisory· Published Mar 11, 2026· Updated Mar 12, 2026
Craft has Reflective XSS via incomplete return URL sanitization
CVE-2026-31859
Description
Craft is a content management system (CMS). The fix for CVE-2025-35939 in craftcms/cms introduced a strip_tags() call in src/web/User.php to sanitize return URLs before they are stored in the session. However, strip_tags() only removes HTML tags (angle brackets) -- it does not inspect or filter URL schemes. Payloads like javascript:alert(document.cookie) contain no HTML tags and pass through strip_tags() completely unmodified, enabling reflected XSS when the return URL is rendered in an href attribute. This vulnerability is fixed in 5.9.7 and 4.17.3.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
craftcms/cmsPackagist | >= 4.15.3, < 4.17.3 | 4.17.3 |
craftcms/cmsPackagist | >= 5.7.5, < 5.9.7 | 5.9.7 |
Affected products
2Patches
Vulnerability mechanics
References
4- github.com/advisories/GHSA-fvwq-45qv-xvhvghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-31859ghsaADVISORY
- github.com/craftcms/cms/commit/cc9921c14897ee2b592a431c2356af8a04ce4cfeghsaWEB
- github.com/craftcms/cms/security/advisories/GHSA-fvwq-45qv-xvhvghsax_refsource_CONFIRMWEB
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