# CVE-2026-48770: Notepad++ WM_COPYDATA COPYDATA_FULL_CMDLINE local DoS crash


- **Severity:** Medium 5.0 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 26 Jun 2026
- **Updated:** 29 Jun 2026
- **Also known as:** GHSA-r39g-3mcw-xcg2

## What is CVE-2026-48770?

CVE-2026-48770 is a medium-severity vulnerability in notepad-plus-plus, published on 26 Jun 2026. 

### Official description

Notepad++ is a free and open-source source code editor. Prior to 8.9.6.1, a local process in the same interactive Windows session can send a malformed WM_COPYDATA message to Notepad++ using the COPYDATA_FULL_CMDLINE path. The handler appears to process COPYDATASTRUCT.lpData as an unbounded NUL-terminated wchar_t* instead of enforcing COPYDATASTRUCT.cbData. This vulnerability is fixed in 8.9.6.1.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-48770?

It affects 1 product.


Products: Notepad-Plus-Plus Notepad\+\+.

## How do I fix CVE-2026-48770?

No fix has been published for CVE-2026-48770 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-48770 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-48770 exists.

Public exploit code:

- Proof-of-concept scripts for three vulnerabilities in Notepad++ <= 8.9.6, patched in v8.9.6.1 (2026-05-26) CVE-2026-48770 / CVE-2026-48778 / CVE-2026-48800 (github_poc): https://github.com/atiilla/Notepad-8.9.6-PoC

## Other vulnerabilities in notepad-plus-plus

- [CVE-2025-15556](https://insights.sbomify.com/CVE-2025-15556/): Notepad++ Download of Code Without Integrity Check (high 7.7, exploited in the wild)
- [CVE-2026-48778](https://insights.sbomify.com/CVE-2026-48778/): Notepad++: Arbitrary Code Execution via config.xml commandLineInterpreter (high 7.8)
- [CVE-2026-48800](https://insights.sbomify.com/CVE-2026-48800/): Notepad++: Arbitrary Code Execution via shortcuts.xml UserCommand Injection (high 7.8)
- [CVE-2026-52884](https://insights.sbomify.com/CVE-2026-52884/): Notepad++: CVE-2026-48800 Bypass (high 7.8)
- [CVE-2023-47452](https://insights.sbomify.com/CVE-2023-47452/): Privilege escalation in n/a (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-48770 and fix it if it is affected.

What it is: CVE-2026-48770 is a medium-severity vulnerability in notepad-plus-plus, published on 26 Jun 2026. 
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-48770 exists.

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-2026-48770/ (Markdown: https://insights.sbomify.com/CVE-2026-48770/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-48770
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-48770
- OSV: https://osv.dev/vulnerability/CVE-2026-48770

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-48770/
Summaries are generated and may contain mistakes; the official description above is the record.