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.
- 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
- None listed
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
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.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-35451 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-35451 exists.
Sources
Also known as GHSA-7w89-7q26-gj7q.