Cross-site scripting in Trix - #VU128365
Published: April 28, 2026
Vulnerability identifier: #VU128365
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Green
CVE-ID: N/A
CWE-ID: CWE-79
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Basecamp
Affected software:
Trix
Trix
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary JavaScript in the victim's browser.
The vulnerability exists due to cross-site scripting in the Level0InputController drag-and-drop handling when processing a crafted application/x-trix-document JSON payload dropped into the editor. A remote attacker can provide a draggable element containing a javascript: URI in the href attribute to execute arbitrary JavaScript in the victim's browser.
User interaction is required to drag and drop attacker-controlled content into the editor, and exploitation only affects environments using the fallback Level0InputController.
Remediation
Install security update from vendor's website.