XSS in Twentyhq Twenty

CVE-2026-35451

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.

Vulnerability class: XSS (Cross-Site Scripting)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.7 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N.

EPSS exploit prediction

EPSS: 0.003 (23.7th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 24th percentile — 23.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-35451: held from 0.004 to 0.003.

EPSS over last 30 days · oldest: 0.004 · newest: 0.003 · change: -0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-35451?
CVE-2026-35451 is a medium-severity vulnerability in Twentyhq Twenty, classified under Cross-site Scripting. CVSS score: 5.7/10. Published 2026-04-21.
How severe is CVE-2026-35451?
Medium severity. CVSS v3 base score is 5.7 out of 10.