Cross-site scripting in Craft CMS - CVE-2026-31859
Published: June 16, 2026
Vulnerability identifier: #VU134661
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Green
CVE-ID: CVE-2026-31859
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Pixel & Tonic, Inc.
Affected software:
Craft CMS
Craft CMS
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary script in the victim's browser.
The vulnerability exists due to cross-site scripting in return URL handling in src/web/User.php when rendering a sanitized return URL in an href attribute. A remote attacker can supply a specially crafted return URL using a javascript: scheme to execute arbitrary script in the victim's browser.
How to mitigate CVE-2026-31859
Install security update from vendor's website.