Client-side Code Execution Vulnerability in Outline Documentation Service
CVE-2026-43887

7.3HIGH

Key Information:

Vendor

Outline

Status
Outline
Vendor
CVE Published:
11 May 2026

What is CVE-2026-43887?

The Outline Documentation Service allows users to collaborate on documents by mentioning one another in comments. However, a significant flaw in versions from 0.84.0 to 1.6.1 exists in its backend processing of the href attributes tied to these mentions. The backend fails to correctly validate or sanitize these attributes, permitting potentially harmful protocols like 'javascript:'. This oversight creates an avenue for client-side code execution, exposing users to security risks. The issue has been addressed and resolved in version 1.7.0.

Affected Version(s)

outline >= 0.84.0, < 1.7.0

References

https://github.com/outline/outline/security/advisories/GH...
x_refsource_CONFIRM

CVSS V3.1

Score:
7.3
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
Low
User Interaction:
Required
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.