# CVE-2026-33955: Notesnook vulnerable to RCE via stored XSS in Note History diff viewer

> Attackers can achieve remote code execution in the Notesnook desktop app via stored XSS in the note history viewer due to insecure HTML rendering and Electron configuration.

- **Severity:** High 8.6 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/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:** 27 Mar 2026
- **Updated:** 3 Apr 2026
- **Also known as:** GHSA-45g3-cv93-q59v

## What is CVE-2026-33955?

CVE-2026-33955 is a high-severity cross-site scripting vulnerability in streetwriters Notesnook Web/Desktop, published on 27 Mar 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

Notesnook is a note-taking app. Prior to version 3.3.11 on Web/Desktop, a cross-site scripting vulnerability stored in the note history comparison viewer can escalate to remote code execution in a desktop application. The issue is triggered when an attacker-controlled note header is displayed using `dangerouslySetInnerHTML` without secure handling. When combined with the full backup and restore feature in the desktop application, this becomes remote code execution because Electron is configured with `nodeIntegration: true` and `contextIsolation: false`. Version 3.3.11 patches the issue.

Weakness: CWE-94 (Improper Control of Generation of Code), CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-33955?

It affects 1 product.


Products: Streetwriters Notesnook Desktop.

## How do I fix CVE-2026-33955?

No fix has been published for CVE-2026-33955 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-33955 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33955 exists.

## Other vulnerabilities in streetwriters Notesnook Web/Desktop

- [CVE-2026-33976](https://insights.sbomify.com/CVE-2026-33976/): Notesnook vulnerable to RCE via stored XSS in Web Clipper rendering (critical 9.7)
- [CVE-2026-42090](https://insights.sbomify.com/CVE-2026-42090/): Notesnook: RCE via stored XSS in note export rendering (critical 9.6)
- [CVE-2026-31876](https://insights.sbomify.com/CVE-2026-31876/): Notesnook has Stored XSS via unsanitized Twitter/X embed URL in editor (`tweetToEmbed`) (medium 5.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-33955 and fix it if it is affected.

What it is: CVE-2026-33955 is a high-severity cross-site scripting vulnerability in streetwriters Notesnook Web/Desktop, published on 27 Mar 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33955 exists.

Affected product: streetwriters Notesnook Web/Desktop. 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-2026-33955/ (Markdown: https://insights.sbomify.com/CVE-2026-33955/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33955
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33955
- OSV: https://osv.dev/vulnerability/CVE-2026-33955

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33955/
Summaries are generated and may contain mistakes; the official description above is the record.