# CVE-2026-48770: 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.

- Web page: https://patchblox.com/security/cve/CVE-2026-48770
- Priority: Routine
- CVSS: 5.0
- EPSS: 0.0014
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jun 26, 2026
- Weakness: CWE-125: Out-of-bounds Read
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-48770

## Description

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

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | Notepad++ | 8.9.6.1 | [Notepad++ 8.9.6.1](https://patchblox.com/security/data/fix/windows-app/notepad-.notepad-8.9.6.1.md) | May 26, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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