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

> Attackers can trigger a stack buffer overflow in Notepad++ via long variable names, potentially leading to code execution or application crashes.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 17 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** GHSA-gv94-327x-2gc5

## What is CVE-2026-54758?

CVE-2026-54758 is a high-severity memory corruption vulnerability in notepad-plus-plus, published on 17 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-787 (Out-of-bounds Write), CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-54758?


## How do I fix CVE-2026-54758?

No fix has been published for CVE-2026-54758 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-54758 being exploited?

There is no known exploitation of CVE-2026-54758 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54758 and fix it if it is affected.

What it is: CVE-2026-54758 is a high-severity memory corruption vulnerability in notepad-plus-plus, published on 17 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-54758 in the wild and no public exploit code.

Affected product: notepad-plus-plus. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-54758/ (Markdown: https://insights.sbomify.com/CVE-2026-54758/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54758
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54758
- OSV: https://osv.dev/vulnerability/CVE-2026-54758

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54758/
Summaries are generated and may contain mistakes; the official description above is the record.