CVE-2026-31859CWE-116CWE-79

Craft has Reflective XSS via incomplete return URL sanitization

Medium · published March 11, 2026

CVSS v4.0
6.9
EPSS
0%
Percentile
17.1
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
6.9 · MEDIUM
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
EPSS
0.00263 · 17.1th percentile
Weaknesses
CWE-116 · Improper Encoding or Escaping of Output; CWE-79 · Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Published
2026-03-11T17:37Z
EPSS history
Timeline
  • 11 MAR 17:37Z
    Craft has Reflective XSS via incomplete return URL sanitization
    cvelistv5