What happened
Outline is a service that allows for collaborative documentation. In versions 0.72.0 through 0.83.0, Outline introduced a feature which facilitates local file system storage capabilities as an optional file storage strategy. This feature allowed a CSP bypass as well as a ContentType bypass that might facilitate further attacks. In the case of self-hosting and using Outline FILE_STORAGE=local on the same domain as the Outline application, a malicious payload can be uploaded as a file attachment and bypass those CSP restrictions, allowing script execution within the context of another user. This is fixed in version 0.84.0.
Affected versions
outline: >= 0.72.0, < 0.84.0 Fixed: See vendor advisory.
Why it matters
Review the vendor advisory and exposure of the affected product to determine operational impact.
Detection & mitigation
- Apply vendor-provided updates or mitigations.
- Review affected product exposure and access logs.
Public PoC references
No public PoC reference has passed the current publication threshold.