# CVE-2026-42090: Notesnook: RCE via stored XSS in note export rendering

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

- **Severity:** Critical 9.6 (`CVSS:3.1/AV:N/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:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 4 May 2026
- **Updated:** 5 May 2026
- **Also known as:** GHSA-fjm8-jg78-89h4

## What is CVE-2026-42090?

CVE-2026-42090 is a critical cross-site scripting vulnerability in streetwriters notesnook, published on 4 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Notesnook is a note-taking app focused on user privacy & ease of use. Prior to Notesnook Web/Desktop version 3.3.15 and prior to Notesnook iOS/Android version 3.3.20, a stored XSS vulnerability in the note export flow can be escalated to remote code execution in the desktop app. The root cause is that exported note fields such as title, headline, and content are inserted into the generated HTML template without HTML escaping. When the note is later exported to PDF, Notesnook renders that HTML into a same-origin, unsandboxed iframe using iframe.srcdoc = .... Injected script executes in the Notesnook origin. In the desktop app, this becomes RCE because Electron is configured with nodeIntegration: true and contextIsolation: false. This issue has been patched in Notesnook Web/Desktop version 3.3.15 and Notesnook iOS/Android version 3.3.20.

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-2026-42090?

It affects 2 products.


Products: Streetwriters Notesnook Desktop, Streetwriters Notesnook Mobile.

## How do I fix CVE-2026-42090?

No fix has been published for CVE-2026-42090 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-42090 being exploited?

There is no known exploitation of CVE-2026-42090 in the wild and no public exploit code.

## Other vulnerabilities in streetwriters notesnook

- [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-2026-33955](https://insights.sbomify.com/CVE-2026-33955/): Notesnook vulnerable to RCE via stored XSS in Note History diff viewer (high 8.6)
- [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-2026-42090 and fix it if it is affected.

What it is: CVE-2026-42090 is a critical cross-site scripting vulnerability in streetwriters notesnook, published on 4 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-42090 in the wild and no public exploit code.

Affected product: streetwriters notesnook. 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-2026-42090/ (Markdown: https://insights.sbomify.com/CVE-2026-42090/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-42090
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-42090
- OSV: https://osv.dev/vulnerability/CVE-2026-42090

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-42090/
Summaries are generated and may contain mistakes; the official description above is the record.