# CVE-2026-73428: Trix: Stored XSS via HTMLParser attribute injection on paste

> CVE-2026-73428: Trix: Stored XSS via HTMLParser attribute injection on paste. CVSS 4.6 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-73428
Last updated: 2026-09-18T20:09:01Z

- Published: 2026-08-13 22:04 UTC · Updated: 2026-09-18 20:09 UTC · Assigner: GitHub\_M
- CVSS: 4.6 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
- EPSS: 0.35%, 29th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-79

## 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 vendors and products

- basecamp: trix

## Tracked companies

- [Basecamp](https://rewindex.com/company/basecamp.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-73428)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-73428)
- [https://github.com/basecamp/trix/commit/9c0a993d9fc2ffe9d56b013b030bc238f9c0557c](https://github.com/basecamp/trix/commit/9c0a993d9fc2ffe9d56b013b030bc238f9c0557c)
- [https://github.com/basecamp/trix/pull/1293](https://github.com/basecamp/trix/pull/1293)
- [https://github.com/basecamp/trix/releases/tag/v2.1.18](https://github.com/basecamp/trix/releases/tag/v2.1.18)
- [https://github.com/basecamp/trix/security/advisories/GHSA-53g2-mvcc-q9x3](https://github.com/basecamp/trix/security/advisories/GHSA-53g2-mvcc-q9x3)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-73428 · Markdown: https://rewindex.com/cve/CVE-2026-73428.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-73428 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:12:10.091Z