CVE-2026-77605

Buffer overflow in NotePad++ version 6.6.9 allows remote attackers to have unspecified impact via a long Time attribute in an Event element in an XML file.

There is a vulnerability in the Notepad app related to improper permission control. Successful exploitation of this vulnerability may lead to privilege escalation, affecting availability and confidentiality.

Notepad++ is a free and open-source source code editor. Prior to 8.9.8, the NPPM_SAVESESSION handler in PowerEditor/src/NppBigSwitch.cpp converts lParam to a sessionInfo pointer and dereferences its nbFile, files, and sessionFilePathName members without checking for null. A process running at the same or a higher Windows integrity level on the same desktop can send NPPM_SAVESESSION with a null lParam, immediately terminating Notepad++ and causing denial of service and loss of unsaved documents. This issue is fixed in version 8.9.8.

Notepad++ prior to 8.9.8 contains a stack buffer overflow in NppParameters::writeSession because a session path derived from the -settingsDir= option is copied into backupPathName[MAX_PATH] without bounds checking. A sufficiently long settings directory causes the buffer to overflow when Notepad++ saves the session, terminating the process via its stack canary and causing denial of service.

Notepad++ from 8.9.7 until 8.9.8 allows the updater and signature verification path to accept a modified GUP.exe file whose embedded certificate metadata remains present even though its Authenticode digest is invalid. An attacker who can replace or plant the updater-related file can cause Notepad++ to launch attacker-modified code when a user triggers the updater path, though the issue does not provide remote code execution by itself.

Notepad++ is a free and open-source source code editor. Prior to 8.9.8, Notepad++ incompletely enforces shortcuts.xml HMAC validation because WM_MACRODLGRUNMACRO, the Run a Macro Multiple Times entry point, calls macroPlayback() without the validation used by command(). A tampered shortcuts.xml macro that is blocked through the Macro menu or a shortcut key can therefore execute through the multi-run dialog and invoke internal Notepad++ commands, including commands that launch external programs, in the current user context. This issue is fixed in version 8.9.8.

Notepad++ prior to 8.9.8 contains a stack buffer overflow in PluginsManager::loadPluginFromPath because the plugin-supplied GetLexerCount() result controls a loop that writes to containers[30] without enforcing NB_MAX_EXTERNAL_LANG. A malicious or compromised plugin that reports more than 30 lexers can write beyond the stack array and corrupt control data, which can permit arbitrary code execution in the Notepad++ process context.

Notepad++ is a free and open-source source code editor. Prior to 8.9.7, macros loaded from an attacker-controlled shortcuts.xml bypass the HMAC validation applied to UserDefinedCommands and can invoke Scintilla actions and the internal Open in Default Viewer command in an elevated Notepad++ process, allowing protected file modification and conditional elevated command execution when a local attacker influences settingsDir and a user triggers the macro. This issue is fixed in version 8.9.7.

Notepad++ is a free and open-source source code editor. Prior to 8.9.7, the WinGup decompress function joins untrusted ZIP entry names to unzipDestTo without canonical containment validation, allowing an entry such as ../mimeTools/mimeTools.dll to overwrite a DLL in a sibling plugin directory and execute attacker-controlled code when Notepad++ next loads that plugin. This issue is fixed in version 8.9.7.

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.