# CVE-2026-54758: Notepad++: Stack Buffer Overflow in expandNppEnvironmentStrs

CVE-2026-54758 is fixed in Notepad++ on 1 platform by Notepad++ 8.9.7 (version 8.9.7), released July 14, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-54758
- Priority: High
- CVSS: 7.8
- EPSS: 0.0019
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 17, 2026
- Weakness: CWE-121: Stack-based Buffer Overflow
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-54758

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | Notepad++ | 8.9.7 | [Notepad++ 8.9.7](https://patchblox.com/security/data/fix/windows-app/notepad-.notepad-8.9.7.md) | Jul 14, 2026 |

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Data as of 2026-11-09T01:18:40Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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