CVE-2026-43887
Stored XSS in Outline Comment Mentions
Publication date: 2026-05-11
Last updated on: 2026-05-11
Assigner: GitHub, Inc.
Description
Description
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| outline | outline | 1.7.0 |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-79 | The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in the Outline service versions from 0.84.0 to 1.6.1, specifically in the comment section where users can mention other users. The backend does not properly validate or sanitize the href attribute in these mentions, allowing potentially dangerous protocols such as "javascript:" to be included. This flaw can lead to client-side code execution, meaning that malicious scripts could run in the context of a user's browser.
How can this vulnerability impact me? :
The vulnerability can lead to client-side code execution, which may allow attackers to execute malicious scripts in the browsers of users interacting with the Outline service. This can result in unauthorized actions such as stealing sensitive information, hijacking user sessions, or performing actions on behalf of the user without their consent.
What immediate steps should I take to mitigate this vulnerability?
To mitigate this vulnerability, upgrade the Outline service to version 1.7.0 or later, where the issue with unsanitized href attributes in user mentions has been fixed.