Trix: Stored XSS via HTMLParser attribute injection on paste

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-73428
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-13 22:17:26 UTC
Updated2026-08-14 18:19:09 UTC
DescriptionTrix 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.

Risk And Classification

Primary CVSS: v3.1 4.6 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

Problem Types: CWE-79 | CWE-79 CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.6MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N
3.1CNADECLARED4.6MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Basecamp Trix affected < 2.1.18 Not specified

References

ReferenceSourceLinkTags
github.com/basecamp/trix/pull/1293 [email protected] github.com
github.com/basecamp/trix/security/advisories/GHSA-53g2-mvcc-q9x3 [email protected] github.com
github.com/basecamp/trix/commit/9c0a993d9fc2ffe9d56b013b030bc238f9c0557c [email protected] github.com
github.com/basecamp/trix/releases/tag/v2.1.18 [email protected] github.com
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