Magento Long Term Support (LTS) is an unofficial, community-driven project provides an alternative to the Magento Community Edition e-commerce platform with a high level of backward compatibility. Prior to version 20.17.0, PHP functions such as `getimagesize()`, `file_exists()`, and `is_readable()` can trigger deserialization when processing `phar://` stream wrapper paths. OpenMage LTS uses these functions with potentially controllable file paths during image validation and media handling. An attacker who can upload a malicious phar file (disguised as an image) and trigger one of these functions with a `phar://` path can achieve arbitrary code execution. Version 20.17.0 patches the issue.