WPvivid Backup & Migration 0.9.117 - 0.9.136 - Admin+ Arbitrary File Upload via wpvivid_upload_import_files

Description

The plugin does not validate the extension of the file it actually stores when handling an import upload: it checks the extension of a separate request field while saving the uploaded file itself with WordPress's upload type-checking disabled, so an authenticated administrator can store a file with an arbitrary extension, including a PHP file, in the plugin's import directory. This is an incomplete fix of CVE-2025-5961, whose extension check was applied to the wrong value.