Outline is an open source, collaborative document editor. A type confusion issue was found in ProseMirror’s rendering process that leads to a Stored Cross-Site Scripting (XSS) vulnerability in Outline. An authenticated user can create a document containing a malicious JavaScript payload. When other users view this document, the malicious Javascript can execute in the origin of Outline. Outline includes CSP rules to prevent third-party code execution, however in the case of self-hosting and having your file storage on the same domain as Outline a malicious payload can be uploaded as a file attachment and bypass those CSP restrictions. This issue has been addressed in release version 0.77.3. Users are advised to upgrade. There are no known workarounds for this vulnerability.

An issue in Outline <= v0.76.1 allows attackers to redirect a victim user to a malicious site via intercepting and changing the state cookie.

Cross-site Scripting (XSS) - Stored in GitHub repository outline/outline prior to 0.70.1.

Cross-site Scripting (XSS) - Stored in GitHub repository outline/outline prior to v0.64.4.

The Outline Designer module 5.x before 5.x-1.4 for Drupal changes each content reader's authentication level to match that of the content author, which might allow remote attackers to gain privileges.