MobaXterm Personal Edition (Portable), in its 26.3 version (Build 5154), allows arbitrary code execution by loading malicious DLLs from a temporary directory that is predictable and can be modified by the user. During startup, the application searches for specific DLLs in this location before resorting to the system’s secure paths, enabling an attacker with local access to place a specially crafted DLL to be executed automatically when the victim launches the application.
The vulnerability has been fixed by the Mobatek team in version 26.4.