The password reset component deployed within Umbraco uses the hostname supplied within the request host header when building a password reset URL. It may be possible to manipulate the URL sent to Umbraco users when so that it points to the attackers server thereby disclosing the password reset token if/when the link is followed. A related vulnerability (CVE-2022-22690) could allow this flaw to become persistent so that all password reset URLs are affected persistently following a successful attack. See the AppCheck advisory for further information and associated caveats.

Within the Umbraco CMS, a configuration element named "UmbracoApplicationUrl" (or just "ApplicationUrl") is used whenever application code needs to build a URL pointing back to the site. For example, when a user resets their password and the application builds a password reset URL or when the administrator invites users to the site. For Umbraco versions less than 9.2.0, if the Application URL is not specifically configured, the attacker can manipulate this value and store it persistently affecting all users for components where the "UmbracoApplicationUrl" is used. For example, the attacker is able to change the URL users receive when resetting their password so that it points to the attackers server, when the user follows this link the reset token can be intercepted by the attacker resulting in account takeover.

Umbraco Forms version 4.0.0 up to and including 8.7.5 and below are vulnerable to a security flaw that could lead to a remote code execution attack and/or arbitrary file deletion. A vulnerability occurs because validation of the file extension is performed after the file has been stored in a temporary directory. By default, files are stored within the application directory structure at %BASEDIR%/APP_DATA/TEMP/FileUploads/. Whilst access to this directory is restricted by the root web.config file, it is possible to override this restriction by uploading another specially crafted web.config file to the temporary directory. It is possible to exploit this flaw to upload a malicious script file to execute arbitrary code and system commands on the server.

Umbraco CMS before 7.15.7 is vulnerable to Open Redirection due to insufficient url sanitization on booting.aspx.

A stored XSS vulnerability exists in Umbraco CMS <= 8.9.1 or current. An authenticated user can inject arbitrary JavaScript code into iframes when editing content using the TinyMCE rich-text editor, as TinyMCE is configured to allow iframes by default in Umbraco CMS.

An authenticated path traversal vulnerability exists during package installation in Umbraco CMS <= 8.9.1 or current, which could result in arbitrary files being written outside of the site home and expected paths when installing an Umbraco package.

A stored XSS vulnerability exists in Umbraco CMS <= 8.9.1 or current. An authenticated user authorized to upload media can upload a malicious .svg file which act as a stored XSS payload.

Editors/LogViewerController.cs in Umbraco through 8.9.1 allows a user to visit a logviewer endpoint even if they lack Applications.Settings access.

This affects all versions of package UmbracoForms. When using the default configuration for upload forms, it is possible to upload arbitrary file types. The package offers a way for users to mitigate the issue. The users of this package can create a custom workflow and frontend validation that blocks certain file types, depending on their security needs and policies.

Umbraco CMS 8.5.3 allows an authenticated file upload (and consequently Remote Code Execution) via the Install Package functionality.