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High, CVSS 7.7amended

Local Privilege Escalation in PyInstaller

CVE-2019-16784GHSA-7fcj-pq9j-wh2r

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (pyinstaller 3.6), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
7.7 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2019-16784: 0.69% estimated exploitation activity in the next 30 days; percentile 53.04 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-7fcj-pq9j-wh2r

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-7fcj-pq9j-wh2r

Agent brief

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# Patch Next advisory brief: CVE-2019-16784

Advisory: Local Privilege Escalation in PyInstaller
IDs: CVE-2019-16784, GHSA-7fcj-pq9j-wh2r
Record: https://patchnext.com/advisories/cve-2019-16784 (revision 3, source checked 26 Oct 2026, 13:22 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: pyinstaller 3.6. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI pyinstaller: affected < 3.6; fixed in 3.6

## Suggested inspection (read-only)
- `python -m pip show pyinstaller`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on pyinstaller.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-7fcj-pq9j-wh2r (OSV record GHSA-7fcj-pq9j-wh2r lists affected ranges: PyPI pyinstaller >=0 <3.6 (fixed))
- Verified: https://github.com/advisories/GHSA-7fcj-pq9j-wh2r (GitHub-reviewed advisory GHSA-7fcj-pq9j-wh2r lists affected ranges: PyPI pyinstaller >=0 <3.6)

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