It has been discovered that Neos is vulnerable to several XSS attacks. Through these vulnerabilities, an attacker could tamper with page rendering, redirect victims to a fake login page, or capture user credentials (such as cookies). With the potential backdoor upload an attacker could gain access to the server itself, to an extent mainly limited by the server setup.
### Reflected Cross-Site Scripting (SXSS) with authentication
A Neos backend user with permission to modify content can insert JavaScript instructions into content elements. The browser will execute the script in "Print" preview mode.
A Neos backend user who can modify his profi
It has been discovered that TYPO3 Neos is vulnerable to Privilege Escalation. Logged in editors could access, create and modify content nodes that exist in the workspace of other editors.
Due to reports it has been validated that internal workspaces in Neos are accessible without authentication. Some users assumed this is a planned feature but it is not. A workspace preview should be an additional feature with respective security measures in place.
Note that this only allows reading of internal workspaces not writing. And for clarification, an internal workspace is a workspace that is non public and doesn't have an owner.
Given that an internal workspace exists in your installation, it is possible to view a page in context of that workspace by opening a link in this format:
https://domain/path/to/page.html@workspace-name
T
Multiple cross-site scripting (XSS) vulnerabilities in Neos CMS allow attackers with the editor role or higher to inject arbitrary script or HTML code using the editor function, the deletion of assets, or a workspace title. The vulnerabilities were found in versions 3.3.29 and 8.0.1 and could also be present in all intermediate versions.
XSS in various backend modules due to (un)escaping in JS notification module
The notification module displaying flash messages unscapes HTML coming from the server, resulting in XSS vulnerabilities with various names and labels of entities (eg. workspace title or media title). This however means you must be a logged in user with respective rights in the first place to leverage the attack vector.