CVE-2026-73428: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in basecamp trix
Trix, a rich text editor by Basecamp, has a stored cross-site scripting (XSS) vulnerability in versions prior to 2.1.18. The issue arises when crafted HTML containing a javascript: URI is pasted into the editor, which can execute when rendered and clicked by another user. This vulnerability is fixed in version 2.1.18. The CVSS score is 4.6, indicating medium severity.
AI Analysis
Technical Summary
CVE-2026-73428 describes a stored cross-site scripting vulnerability in Basecamp's Trix rich text editor before version 2.1.18. The vulnerability occurs because HTMLParser processes a mock attachment in a <span> element with an empty data-trix-attachment attribute, causing data-trix-attributes to be applied improperly to a plain string piece. The StringPiece.fromJSON method accepts an unvalidated href attribute, allowing a javascript: URI to be injected into the document model. This malicious URI can execute when another user renders and interacts with the content. Server-side HTML sanitization can neutralize the payload on save. The issue is resolved in Trix version 2.1.18.
Potential Impact
An attacker can inject a stored XSS payload via crafted HTML pasted into the editor, potentially leading to execution of arbitrary JavaScript in the context of other users viewing the content. This can result in limited confidentiality and integrity impact as per the CVSS vector (C:L, I:L, A:N). There is no known exploitation in the wild at this time.
Mitigation Recommendations
Upgrade Trix to version 2.1.18 or later, where this vulnerability is fixed. Alternatively, applying server-side HTML sanitization on saved content can neutralize the malicious payload. No other specific mitigations are indicated.
CVE-2026-73428: CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in basecamp trix
Description
Trix, a rich text editor by Basecamp, has a stored cross-site scripting (XSS) vulnerability in versions prior to 2.1.18. The issue arises when crafted HTML containing a javascript: URI is pasted into the editor, which can execute when rendered and clicked by another user. This vulnerability is fixed in version 2.1.18. The CVSS score is 4.6, indicating medium severity.
CVSS v3.1
Score 4.6medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-73428 describes a stored cross-site scripting vulnerability in Basecamp's Trix rich text editor before version 2.1.18. The vulnerability occurs because HTMLParser processes a mock attachment in a <span> element with an empty data-trix-attachment attribute, causing data-trix-attributes to be applied improperly to a plain string piece. The StringPiece.fromJSON method accepts an unvalidated href attribute, allowing a javascript: URI to be injected into the document model. This malicious URI can execute when another user renders and interacts with the content. Server-side HTML sanitization can neutralize the payload on save. The issue is resolved in Trix version 2.1.18.
Potential Impact
An attacker can inject a stored XSS payload via crafted HTML pasted into the editor, potentially leading to execution of arbitrary JavaScript in the context of other users viewing the content. This can result in limited confidentiality and integrity impact as per the CVSS vector (C:L, I:L, A:N). There is no known exploitation in the wild at this time.
Mitigation Recommendations
Upgrade Trix to version 2.1.18 or later, where this vulnerability is fixed. Alternatively, applying server-side HTML sanitization on saved content can neutralize the malicious payload. No other specific mitigations are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-12T14:32:11.796Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a7e4130bf8831d539e0525e
Added to database: 08/13/2026, 22:12:00 UTC
Last enriched: 08/13/2026, 22:27:05 UTC
Last updated: 08/14/2026, 00:29:21 UTC
Views: 6
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