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CVE-2019-16784 — Local Privilege Escalation present only on the Windows version of PyInstaller

Affected: PyInstaller

In PyInstaller before version 3.6, only on Windows, a local privilege escalation vulnerability is present in this particular case: If a software using PyInstaller in "onefile" mode is launched by a privileged user (at least more than the current one) which have his "TempPath" resolving to a world writable directory. This is the case for example if the software is launched as a service or as a scheduled task using a system account (TempPath will be C:\Windows\Temp). In order to be exploitable the software has to be (re)started after the attacker launch the exploit program, so for a service launched at startup, a service restart is needed (e.g. after a crash or an upgrade).

GHSA-7fcj-pq9j-wh2r — Local Privilege Escalation in PyInstaller

Affected: PyPI: PyInstaller

### Impact

Local Privilege Escalation in all Windows software frozen by PyInstaller in "onefile" mode.

The vulnerability is present only on Windows and in this particular case: If a **software frozen by PyInstaller in "onefile" mode** is launched by a (privileged) user who has **his/her "TempPath" resolving to a world writable directory**. This is the case e.g. if the software is launched as a service or as a scheduled task using a system account (in which case TempPath will default to C:\Windows\Temp).

In order to be exploitable the software has to be (re)started after the attacker has launched the exploit program. So for a service launched at startup, a service restart is needed (e.g. after a crash or an upgrade).

While PyInstaller itself was not vulnerable, all Windows software frozen by PyInstaller in "onefile" mode is vulnerable.

CVSSv3 score 7.0 (High) CVSSv3 vector CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected - all Windows software frozen by PyInstaller in "onefile" mode

No affected - PyInstaller itself (except if frozen by PyInstaller in "onefile" mode on Windows) - software frozen in "one*dir*" mode - other platforms (GNU/Linux, OS X, BSD, etc.)

### Patches The problem is patched in commits 42a67148b3bdf9211fda8499fdc5b63acdd7e6cc (fixed code) and be948cf0954707671aa499da17b10c86b6fa5e5c (recompiled bootloaders). Users should upgrade to PyInstaller version 3.6 and rebuild their software.

### Workarounds There is no known workaround. Users using PyI…

PYSEC-2020-175

Affected: PyPI: pyinstaller