Notepad-plus-plus CVEs & Vulnerabilities

Notepad++ is a free and open-source source code editor. Prior to 8.9.6.4, NppCommands.cpp checks the HMAC of the on-disk shortcuts.xml at the moment a user command fires (Time-of-Check). However, the command payload is taken from the in-memory _userCommands vector, which is populated at application startup and never re-synchronized with the on-disk file (Time-of-Use). Swapping shortcuts.xml between startup and command execution causes the HMAC check to validate a clean file while a malicious command runs. An attacker with write access to shortcuts.xml places a malicious version on disk before launch, then immediately restores the legitimate file. The HMAC check at execution time validates the restored legitimate file (check passes), while the malicious payload executes from memory. This vulnerability is fixed in 8.9.6.4.

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.

Notepad++ is a free and open-source source code editor. Prior to 8.9.6.1, the <Command> tag text content inside <UserDefinedCommands> in shortcuts.xml is read by NppXml::value(aNode) (Parameters.cpp:3658) in the feedUserCmds() function and stored in UserCommand._cmd without any validation. When the user clicks the corresponding entry in the Run menu, NppCommands.cpp:4264 creates a Command object with string2wstring(ucmd.getCmd()) and calls run(), which invokes ShellExecute (RunDlg.cpp:221) with the attacker-controlled string as the executable path. The injected command appears as a normal menu item in the Run menu, making it a viable persistence mechanism. This vulnerability is fixed in 8.9.6.1.

Notepad++ is a free and open-source source code editor. Prior to 8.9.6.1, the <GUIConfig name="commandLineInterpreter"> tag in config.xml is read by NppXml::value() (Parameters.cpp:6430) and stored in _nppGUI._commandLineInterpreter without any validation, whitelist, or digital signature check. When the user triggers IDM_FILE_OPEN_CMD (File → Open Containing Folder → cmd), NppCommands.cpp:228 creates a Command object with this value and calls run(), which invokes ShellExecute (RunDlg.cpp:221) with the attacker-controlled string as the executable path. This vulnerability is fixed in 8.9.6.1.

Notepad++ is a free and open-source source code editor. Prior to 8.9.6.1, a local process in the same interactive Windows session can send a malformed WM_COPYDATA message to Notepad++ using the COPYDATA_FULL_CMDLINE path. The handler appears to process COPYDATASTRUCT.lpData as an unbounded NUL-terminated wchar_t* instead of enforcing COPYDATASTRUCT.cbData. This vulnerability is fixed in 8.9.6.1.

Notepad++ is a free and open-source source code editor. From 8.9.4 until 8.9.6, Notepad++ contains a local privilege escalation vulnerability in the installer. During installation, the installer invokes powershell.exe without using an absolute path after setting the working directory to the installation contextMenu directory. If an attacker can pre-place a malicious powershell.exe in a user-writable custom installation directory, and a privileged user later runs the installer and selects that directory, the attacker-controlled executable is launched with the elevated privileges of the installer. This vulnerability is fixed in 8.9.6.

Notepad++ 8.9.3 contains a format string injection vulnerability in the Find Results panel handler that allows attackers to cause denial of service and information disclosure by crafting a malicious nativeLang.xml language pack file. Attackers can distribute a poisoned language pack through community channels that triggers format string interpretation when a user performs search operations, leading to access violations and potential leakage of stack or register contents.

Notepad++ is a free and open-source source code editor. An Unsafe Search Path vulnerability (CWE-426) exists in versions prior to 8.9.2 when launching Windows Explorer without an absolute executable path. This may allow execution of a malicious explorer.exe if an attacker can control the process working directory. Under certain conditions, this could lead to arbitrary code execution in the context of the running application. Version 8.9.2 patches the issue.