CVE-2026-31859

Craft has Reflective XSS via incomplete return URL sanitization

Published Mar 11, 2026 CVSS 4.0 · 6.9 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-fvwq-45qv-xvhv CraftCMS vulnerable to reflective XSS via incomplete return URL sanitization
History
Type Values Removed Values Added
First Time appeared Craftcms craft Cms
CPEs cpe:2.3:a:craftcms:craft_cms:*:*:*:*:*:*:*:*
Vendors & Products Craftcms craft Cms
Metrics cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Craftcms
Craftcms craftcms
Vendors & Products Craftcms
Craftcms craftcms
Type Values Removed Values Added
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.
Title Craft has Reflective XSS via incomplete return URL sanitization
Weaknesses CWE-116
CWE-79
References
Metrics cvssV4_0

{'score': 6.9, 'vector': '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'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Mar 12, 2026, 2:00 PM
Reserved
Mar 9, 2026, 7:02 PM
Status
Analyzed
Published
Mar 11, 2026, 6:16 PM
Modified
Jun 17, 2026, 10:34 AM