Szafir and Szafir Weryfikująca are vulnerable to XML External Entity (XXE) injection. When a user signs or verify a crafted XML file containing a `DOCTYPE` with an external DTD reference, the parser processes external entities, allowing an attacker to read arbitrary files from the victim's filesystem. This issue was fixed in Szafir version 2.0 build 708. Szafir Weryfikująca is no longer supported (End of Life) and has not been fixed.