Trix: Stored XSS via HTMLParser attribute injection on paste

Description

The Trix editor, in versions prior to 2.1.18, is vulnerable to XSS when crafted HTML is pasted into the editor. The HTMLParser processed a mock attachment, a <span> carrying an empty data-trix-attachment="{}".

Recommendation

Update the trix package to the latest compatible version. Followings are version details:

• Affected version(s): < 2.1.18
• Patched version(s): 2.1.18

References

• GHSA-53g2-mvcc-q9x3
• CVE-2026-73428
• CWE-79
• CAPEC-310
• OWASP 2021-A3
• OWASP 2021-A6