The vulnerability stems from insecure XML parsing in layout processing. Magento's DOM configuration (Dom::__construct) is the core XML parser that would require LIBXML_NOENT restriction. LayoutUpdate::load is the entry point for admin-controlled XML that would trigger the vulnerable parsing. These functions would appear in stack traces when processing malicious XML layouts. The confidence is high for Dom::__construct as it's the primary XML parser, and medium for LayoutUpdate::load as it's the likely injection point based on vulnerability description.