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

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-01-14 · updated 2026-06-17
Weakness: CWE-250

Description

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).

Affected products

pyinstaller: before 3.6 — fixed in 3.6

How to fix

Upgrade to a fixed version: pyinstaller 3.6. Check the vendor advisory for mitigations.

References

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