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.

High
CVSS
8.6
No vendor severity
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0022
13th percentile

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

ProductFixed inFixReleased
Windows apps
Notepad++ 8.9.6.1 Notepad++ 8.9.6.1 May 26, 2026

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