# CVE-2026-86056: Notepad++: Null pointer dereference in NPPM_SAVESESSION message handler causes crash (DoS)

> A local attacker can crash Notepad++ by sending a crafted message with null parameters, causing denial of service and loss of unsaved work.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 22 Sep 2026
- **Updated:** 22 Sep 2026
- **Also known as:** GHSA-j85c-6wc9-p98p

## What is CVE-2026-86056?

CVE-2026-86056 is a medium-severity vulnerability in notepad-plus-plus, published on 22 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Notepad++ is a free and open-source source code editor. Prior to 8.9.8, the NPPM_SAVESESSION handler in PowerEditor/src/NppBigSwitch.cpp converts lParam to a sessionInfo pointer and dereferences its nbFile, files, and sessionFilePathName members without checking for null. A process running at the same or a higher Windows integrity level on the same desktop can send NPPM_SAVESESSION with a null lParam, immediately terminating Notepad++ and causing denial of service and loss of unsaved documents. This issue is fixed in version 8.9.8.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-86056?


## How do I fix CVE-2026-86056?

No fix has been published for CVE-2026-86056 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-86056 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-86056 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-86056 and fix it if it is affected.

What it is: CVE-2026-86056 is a medium-severity vulnerability in notepad-plus-plus, published on 22 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-86056 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-2026-86056/ (Markdown: https://insights.sbomify.com/CVE-2026-86056/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-86056
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-86056
- OSV: https://osv.dev/vulnerability/CVE-2026-86056

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-86056/
Summaries are generated and may contain mistakes; the official description above is the record.