# CVE-2026-31876: Notesnook has Stored XSS via unsanitized Twitter/X embed URL in editor (`tweetToEmbed`)

> Attackers can inject malicious scripts via Twitter embed URLs in Notesnook, potentially stealing user data or taking over accounts.

- **Severity:** Medium 5.4 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 11 Mar 2026
- **Updated:** 12 Mar 2026
- **Also known as:** GHSA-jprx-2w2h-4rh5

## What is CVE-2026-31876?

CVE-2026-31876 is a medium-severity cross-site scripting vulnerability in streetwriters notesnook, published on 11 Mar 2026. Any signed-in user can exploit it over the network, 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 3.3.9, a Stored Cross-Site Scripting (XSS) vulnerability existed in Notesnook's editor embed component when rendering Twitter/X embed URLs. The tweetToEmbed() function in component.tsx interpolated the user-supplied URL directly into an HTML string without escaping, which was then assigned to the srcdoc attribute of an <iframe>. This vulnerability is fixed in 3.3.9.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-31876?

It affects 2 products.


Products: Streetwriters Notesnook Desktop, Streetwriters Notesnook Mobile.

## How do I fix CVE-2026-31876?

No fix has been published for CVE-2026-31876 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-31876 being exploited?

There is no known exploitation of CVE-2026-31876 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-2026-42090](https://insights.sbomify.com/CVE-2026-42090/): Notesnook: RCE via stored XSS in note export rendering (critical 9.6)
- [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)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31876 and fix it if it is affected.

What it is: CVE-2026-31876 is a medium-severity cross-site scripting vulnerability in streetwriters notesnook, published on 11 Mar 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-31876 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-2026-31876/ (Markdown: https://insights.sbomify.com/CVE-2026-31876/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31876
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31876
- OSV: https://osv.dev/vulnerability/CVE-2026-31876

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31876/
Summaries are generated and may contain mistakes; the official description above is the record.