The vulnerability in @a2ui/web_core arises from the openUrl function passing an agent-controlled URL directly to window.open() without validating the URI scheme. This allows an attacker to supply a javascript: URI as the url argument in a Button component's functionCall action. When a user clicks the button, arbitrary JavaScript executes in the browser origin of the victim application, resulting in a stored or reflected cross-site scripting (XSS) vulnerability. The issue affects all versions from 0.9.0 onwards and requires no special configuration to be exploitable. The CVSS v3.1 score is 6.1, indicating medium severity with network attack vector, low attack complexity, no privileges required, user interaction required, scope changed, and low impact on confidentiality and integrity, with no impact on availability.

Successful exploitation allows an attacker to execute arbitrary JavaScript in the context of the victim application's browser origin. This can lead to theft of sensitive information, session hijacking, or other actions permitted by the browser context. The vulnerability is classified as a cross-site scripting (XSS) issue with medium severity (CVSS 6.1). There are no known exploits in the wild at this time.

No official patch or fix is currently documented. Since this advisory is a duplicate and no patch links are provided, patch status is not yet confirmed — check the vendor advisory GHSA-72qq-p3r5-f7wq for current remediation guidance. Until a fix is available, avoid using untrusted input in the openUrl function or implement strict validation of URL schemes to prevent javascript: URIs from being passed to window.open().