Outline up to 1.7.0 API Endpoint subscriptions.create authorization

Summaryinfo

A vulnerability described as problematic has been identified in Outline up to 1.7.0. Impacted is the function subscriptions.create of the component API Endpoint. Such manipulation leads to authorization. This vulnerability is documented as CVE-2026-43890. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Outline up to 1.7.0. It has been rated as problematic. Affected by this issue is the function subscriptions.create of the component API Endpoint. The manipulation with an unknown input leads to a authorization vulnerability. Using CWE to declare the problem leads to CWE-639. The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. Impacted is confidentiality. CVE summarizes:

Outline is a service that allows for collaborative documentation. From 0.84.0 to 1.7.0, the subscriptions.create API endpoint in server/routes/api/subscriptions/subscriptions.ts exhibits a broken authorization pattern. When both collectionId and documentId are supplied in the request, the route handler authorizes ONLY the collection branch (line 125 if (collectionId)), while the downstream subscriptionCreator command at server/commands/subscriptionCreator.ts writes the subscription against the documentId (which was never validated). The result is a subscription record pinning the attacker's user to a victim document the attacker has no read access to, on any team in the instance. The schema (server/routes/api/subscriptions/schema.ts) only enforces "at least one of collectionId/documentId" via .refine() — it does NOT enforce mutual exclusivity, so passing both is a valid, schema-conforming request. This vulnerability is fixed in 1.7.1.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-43890 since 05/04/2026. The exploitation is known to be easy. The attack may be launched remotely. Technical details are known, but there is no available exploit.

Upgrading to version 1.7.1 eliminates this vulnerability.

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Productinfo

Name

• Outline

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7.0

Website

• Product: https://github.com/outline/outline/

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