CVE-2026-49836: psd-tools vulnerable to arbitrary file write via smart-object filename

In psd-tools (all releases exposing the SmartObject API through v1.17.0), SmartObject.save() writes an embedded smart object to a path taken verbatim from the PSD file. Because that name is attacker-controlled and unsanitised, a tool that extracts embedded objects from an untrusted .psd can be made to write attacker-chosen bytes to an attacker-chosen path (absolute or ../-traversing), outside its intended output directory.

A secondary issue in SmartObject.open() for external-kind smart objects allows the attacker-controlled fullPath descriptor to be used as an arbitrary file read path, enabling exfiltration of the read content to the controlled write destination. Both issues are fixed in v1.17.1.