Notepad++ WM_COPYDATA COPYDATA_FULL_CMDLINE local DoS crash
CVE-2026-48770 is fixed in Notepad++ on 1 platform by Notepad++ 8.9.6.1 (version 8.9.6.1), released May 26, 2026. It is not reported as exploited. Patch Radar priority: Routine.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Windows apps | |||
| Notepad++ | 8.9.6.1 | Notepad++ 8.9.6.1 | May 26, 2026 |
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