XSS in Basecamp Trix

CVE-2026-73426

Trix is a what-you-see-is-what-you-get rich text editor for everyday writing. Prior to 2.1.17, Trix is vulnerable to cross-site scripting when a data-trix-serialized-attributes attribute bypasses the DOMPurify sanitizer. An attacker can craft HTML containing a data-trix-serialized-attributes attribute with a malicious payload that, when rendered, executes arbitrary JavaScript in the user's session and may perform unauthorized actions or disclose sensitive information. This issue is fixed in version 2.1.17.

Vulnerability class: XSS (Cross-Site Scripting)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 4.6 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (22.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 23rd percentile — 22.8% 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-2026-73426: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-73426?
CVE-2026-73426 is a medium-severity vulnerability in Basecamp Trix, classified under Cross-site Scripting. CVSS score: 4.6/10. Published 2026-08-18.
How severe is CVE-2026-73426?
Medium severity. CVSS v3 base score is 4.6 out of 10.