{"id":"CVE-2026-33430","aliases":["GHSA-r3r2-35v9-v238","PYSEC-2026-27"],"url":"https://o3.security/vulnerability/CVE-2026-33430","summary":"Briefcase: Windows MSI Installer Privilege Escalation via Insecure Directory Permissions","details":"### Impact\n\nIf 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.\n\n### Patches\n\nThe problem is caused by the template used to generate the WXS file for Windows projects. It was fixed with the following PRs:\n\n* beeware/briefcase-windows-app-template#86\n* beeware/briefcase-windows-VisualStudio-template#85\n\nThese 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.\n\n### Workarounds\n\nThe 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.\n\n### Resources\n\nbeeware/briefcase#2759 is a formal bug report of the problem.","published":"2026-03-26T16:54:42.992Z","modified":"2026-10-28T02:31:08.257034927Z","cvss":{"score":7.3,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H"},"epss":{"score":0.00132,"percentile":0.03229,"asOf":"2026-08-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"PyPI","name":"briefcase","fixedVersion":"0.3.26"}],"fix":{"url":"https://github.com/beeware/briefcase-windows-VisualStudio-template/pull/85","label":"beeware/briefcase-windows-VisualStudio-template#85"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33430.json"},{"type":"ADVISORY","url":"https://github.com/beeware/briefcase/security/advisories/GHSA-r3r2-35v9-v238"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33430"},{"type":"REPORT","url":"https://github.com/beeware/briefcase/issues/2759"},{"type":"FIX","url":"https://github.com/beeware/briefcase-windows-VisualStudio-template/pull/85"},{"type":"FIX","url":"https://github.com/beeware/briefcase-windows-app-template/pull/86"},{"type":"PACKAGE","url":"https://github.com/beeware/briefcase"},{"type":"WEB","url":"https://github.com/pypa/advisory-database/tree/main/vulns/briefcase/PYSEC-2026-27.yaml"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-28T02:31:08.257034927Z"}}