Vulnerability · Published Aug 13, 2026 · Assigned by GitHub_M
CVE-2026-73428Trix: Stored XSS via HTMLParser attribute injection on paste
Medium 4.6
In plain English
A medium-severity cross-site scripting in trix from basecamp. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Trix is a what-you-see-is-what-you-get rich text editor for everyday writing. Prior to 2.1.18, Trix is vulnerable to stored cross-site scripting when crafted HTML is pasted into the editor. HTMLParser processes a mock attachment in a `<span>` with an empty `data-trix-attachment="{}"` value, causing data-trix-attributes to be applied to a plain string piece. StringPiece.fromJSON accepts an unvalidated href, allowing a javascript: URI to enter the document model and serialized HTML and execute when another user renders and clicks the content. Applications that apply server-side HTML sanitization can neutralize the payload on save. This issue is fixed in version 2.1.18.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| RubyGems | action_text-trix | 2.1.18 | GHSA-53g2-mvcc-q9x3 |
| npm | trix | 2.1.18 | GHSA-53g2-mvcc-q9x3 |
Affected products (as reported)
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
References
- https://github.com/basecamp/trix/security/advisories/GHSA-53g2-mvcc-q9x3 x_refsource_CONFIRM
- https://github.com/basecamp/trix/pull/1293 x_refsource_MISC
- https://github.com/basecamp/trix/commit/9c0a993d9fc2ffe9d56b013b030bc238f9c0557c x_refsource_MISC
- https://github.com/basecamp/trix/releases/tag/v2.1.18 x_refsource_MISC