CVE-2026-73037 is a reflected cross-site scripting vulnerability affecting Next AI Draw.io versions 0.2.1 through 0.4.16. The vulnerability arises because the mcp query parameter is inserted into HTML and JavaScript contexts without proper neutralization, enabling attackers to execute arbitrary scripts in the context of the localhost origin. This can be exploited by crafting malicious URLs that, when visited, allow unauthorized JavaScript execution potentially leading to data exfiltration of diagram sessions and API information. The CVSS 4.0 vector indicates network attack vector, low attack complexity, no privileges required, user interaction needed, and low scope and impact on confidentiality, integrity, and availability.

Successful exploitation allows an attacker to execute arbitrary JavaScript code within the localhost origin, which can lead to unauthorized access and exfiltration of sensitive diagram session data and API information. The impact is limited to the scope of the affected web application and requires user interaction to trigger the malicious URL.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, users should avoid clicking on untrusted links containing the mcp query parameter and consider implementing web application firewall rules to detect and block suspicious input patterns targeting this parameter.