CVE-2026-54758: Notepad-Plus-Plus

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

Notepad++ is a free and open-source source code editor. Prior to 8.9.7, the expandNppEnvironmentStrs function in PowerEditor/src/WinControls/StaticDialog/RunDlg/RunDlg.cpp copies a Notepad++ variable name between $( and ) into the fixed-size wchar_t str[MAX_PATH] stack buffer without bounding the m loop index, allowing a name of 260 or more characters to corrupt adjacent stack data, terminate the process through __report_gsfailure, and potentially execute code. This issue is fixed in version 8.9.7.

Affected products

• Notepad-Plus-Plus Notepad-Plus-Plus: before 8.9.7 (fixed in 8.9.7)

Published 2026-08-17. Last modified 2026-09-09.