The vulnerability stems from using jQuery 3.4.1, which contains XSS vulnerabilities in DOM manipulation methods like .html() and .append() when processing untrusted HTML. However, the provided information does not include specific code examples, file paths, or namespace details from the pimcore/admin-ui-classic-bundle implementation that directly utilize these jQuery methods with untrusted input. While the jQuery methods themselves are known to be vulnerable, the advisory focuses on the library version rather than specific vulnerable functions in the PIMCore codebase. Without access to the actual implementation details or commit diffs, we cannot confidently identify specific application-level functions that trigger the vulnerability.