Outline is a service that allows for collaborative documentation. Outline implements an Email OTP login flow for users not associated with an Identity Provider. Starting in version 0.86.0 and prior to version 1.6.0, Outline does not invalidate OTP codes based on amount or frequency of invalid submissions, rather it relies on the rate limiter to restrict attempts. Consequently, identified bypasses in the rate limiter permit unrestricted OTP code submissions within the codes lifetime. This allows attackers to perform brute force attacks which enable account takeover. Version 1.6.0 fixes the issue.

Outline is a service that allows for collaborative documentation. Prior to 1.5.0, the events.list API endpoint, used for retrieving activity logs, contains a logic flaw in its filtering mechanism. It allows any authenticated user to retrieve activity events associated with documents that have no collection (e.g., Private Drafts, Deleted Documents), regardless of the user's actual permissions on those documents. While the document content is not directly exposed, this vulnerability leaks sensitive metadata (such as Document IDs, user activity timestamps, and in some specific cases like the Document Title of Permanent Delete). Crucially, leaking valid Document IDs of deleted drafts removes the protection of UUID randomness, making High-severity IDOR attacks (such as the one identified in documents.restore) trivially exploitable by lowering the attack complexity. Version 1.5.0 fixes the issue.

Outline is a service that allows for collaborative documentation. Prior to 1.4.0, an Insecure Direct Object Reference (IDOR) vulnerability in the document restoration logic allows any team member to unauthorizedly restore, view, and seize ownership of deleted drafts belonging to other users, including administrators. By bypassing ownership validation during the restore process, an attacker can access sensitive private information and effectively lock the original owner out of their own content. Version 1.4.0 fixes the issue.

Outline is a service that allows for collaborative documentation. Prior to 1.4.0, during the JSON import process, the value of attachments[].key from the imported JSON is passed directly to path.join(rootPath, node.key) and then read using fs.readFile without validation. By embedding path traversal sequences such as ../ or absolute paths, an attacker can read arbitrary files on the server and import them as attachments. This vulnerability is fixed in 1.4.0.

Outline is a service that allows for collaborative documentation. Prior to 1.1.0, a privilege escalation vulnerability exists in the Outline document management system due to inconsistent authorization checks between user and group membership management endpoints. This vulnerability is fixed in 1.1.0.

Outline 1.6.0 contains an unquoted service path vulnerability that allows local attackers to potentially execute arbitrary code with elevated system privileges. Attackers can exploit the unquoted service path in the OutlineService executable to inject malicious code that will be executed with LocalSystem permissions.