Outline’s document restoration logic before version 1.4.0 contains an insecure direct object reference (IDOR) that lets any authenticated team member restore, view, and seize ownership of deleted drafts belonging to other users, including administrators. This flaw bypasses ownership validation, allowing attackers to read sensitive private content and lock the original owner out of their own documents. The primary impact is the compromise of confidentiality and omission of proper authorization controls, categorised as CWE‑639.

The affected product is Outline by getoutline. All deployments running any version prior to 1.4.0 are vulnerable, regardless of environment or deployment method. Versions 1.4.0 and later include the fix.

The CVSS score of 8.1 signals a high severity vulnerability, while the EPSS score of less than 1 % indicates a low current probability of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog. Attackers must be authenticated team members with access to the collaboration platform; the exploit requires interaction with the document restoration endpoint to trigger the IDOR. If successfully exploited, the attacker gains unauthorized information disclosure and ownership control over deleted documents.