Piwigo before v16.4.0 is vulnerable to arbitrary file read and remote code execution in image upload handling when using the Imagick library due to insufficient validation and unsafe processing of user-supplied image files. By abusing format confusion (e.g., disguising SVG content as PNG), an attacker can trigger unintended interpretation of embedded SVG elements that reference local files. In more advanced scenarios, the Imagick support for Magick Scripting Language (MSL) may be abused to process attacker-controlled instructions, potentially leading to unauthorized server-side file writes and remote code execution, depending on configuration. This has been patched in 16.4.0.