# CVE-2026-35451: Twenty: Stored XSS via BlockNote FileBlock

> Attackers can inject malicious JavaScript into file blocks, leading to arbitrary code execution when users click the attachment.

- **Severity:** Medium 5.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/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:** 21 Apr 2026
- **Updated:** 21 Apr 2026
- **Also known as:** GHSA-7w89-7q26-gj7q

## What is CVE-2026-35451?

CVE-2026-35451 is a medium-severity cross-site scripting vulnerability in twentyhq twenty, published on 21 Apr 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

Twenty is an open source CRM. Prior to 1.20.6, a Stored Cross-Site Scripting (XSS) vulnerability exists in the BlockNote editor component. Due to a lack of protocol validation in the FileBlock component and insufficient server-side inspection of block content, an attacker can inject a javascript: URI into the url property of a file block. This allows the execution of arbitrary JavaScript when a user clicks on the malicious file attachment. This vulnerability is fixed in 1.20.6.

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

## Which versions are affected by CVE-2026-35451?


## How do I fix CVE-2026-35451?

No fix has been published for CVE-2026-35451 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-35451 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-35451 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-35451 and fix it if it is affected.

What it is: CVE-2026-35451 is a medium-severity cross-site scripting vulnerability in twentyhq twenty, published on 21 Apr 2026. Any signed-in user can exploit it over the 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-2026-35451 exists.

Affected product: twentyhq twenty. 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-2026-35451/ (Markdown: https://insights.sbomify.com/CVE-2026-35451/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-35451
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-35451
- OSV: https://osv.dev/vulnerability/CVE-2026-35451

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-35451/
Summaries are generated and may contain mistakes; the official description above is the record.