Notepad++: CVE-2026-48800 Bypass

Notepad++ is a free and open-source source code editor. In v8.9.6.1, isInTrustedDirectory() does NOT canonicalize the path before checking. It uses a prefix-based check (PathIsPrefix() or equivalent) that matches paths starting with trusted directory strings. A path traversal using ..\..\ after a trusted directory prefix passes the check while resolving to an untrusted location. The CVE-2026-48800 patch adds isInTrustedDirectory() validation in Command::run() (RunDlg.cpp) before calling ShellExecute(). This function checks whether the resolved executable path is under a trusted directory. This vulnerability is fixed in 8.9.6.2.