CVE-2026-33430

Workarounds

The change from beeware/briefcase-windows-app-template#86 can be added to any existing Briefcase .wxs file generated by Briefcase 0.3.24 or later.

Resources

beeware/briefcase#2759 is a formal bug report of the problem.

If a developer uses Briefcase to produce an Windows MSI installer for a project, and that project is installed for All Users (i.e., per-machine scope), the installation process creates an directory that inherits all the permissions of the parent directory. Depending on the location chosen by the installing user, this may allow a low privilege but authenticated user to replace or modify the binaries installed by the application. If an administrator then runs the altered binary, the binary will run with elevated privileges.

A file, directory, or other resource is assigned permissions that allow broader access than intended. Typical impact: unauthorized read, modification, or execution of the resource.

CVE-2026-33430 has a CVSS score of 7.3 (High). The vector is requires local access, low privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.3.26); upgrading removes the vulnerable code path.

Kodem intelligence

The problem is caused by the template used to generate the WXS file for Windows projects. It was fixed with the following PRs:

• beeware/briefcase-windows-app-template#86
• beeware/briefcase-windows-VisualStudio-template#85

These patches have been backported to the templates used in Briefcase 0.3.26, 0.4.0, and 0.4.1. Re-running briefcase create on your Briefcase project will result in the updated templates being used.

1. What is CVE-2026-33430? CVE-2026-33430 is a high-severity incorrect permission assignment for critical resource vulnerability in briefcase (pip), affecting versions >= 0.3.0, < 0.3.26. It is fixed in 0.3.26. A file, directory, or other resource is assigned permissions that allow broader access than intended.
2. How severe is CVE-2026-33430? CVE-2026-33430 has a CVSS score of 7.3 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of briefcase are affected by CVE-2026-33430? briefcase (pip) versions >= 0.3.0, < 0.3.26 is affected.
4. Is there a fix for CVE-2026-33430? Yes. CVE-2026-33430 is fixed in 0.3.26. Upgrade to this version or later.
5. Is CVE-2026-33430 exploitable, and should I be worried? Whether CVE-2026-33430 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-33430 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-33430? Upgrade briefcase to 0.3.26 or later.