# CVE-2026-85279: Notepad++: Stack Buffer Overflow in Plugin Lexer Loading via Unchecked GetLexerCount() Return Value

CVE-2026-85279 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: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-85279
- Priority: High
- CVSS: 8.6
- EPSS: 0.0022
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 22, 2026
- Weakness: CWE-121: Stack-based Buffer Overflow
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-85279

## Description

Notepad++ is a free and open-source source code editor. Prior to 8.9.8, Notepad++ contains a stack buffer overflow in PluginsManager::loadPluginFromPath in PowerEditor/src/MISC/PluginsManager/PluginsManager.cpp 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. This issue is fixed in version 8.9.8.

## 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 2026-11-08T19:12:23Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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