SilverStripe through 4.4.x before 4.4.5 and 4.5.x before 4.5.2 allows Reflected XSS on the login form and custom forms. Silverstripe Forms allow malicious HTML or JavaScript to be inserted through non-scalar FormField attributes, which allows performing XSS (Cross-Site Scripting) on some forms built with user input (Request data). This can lead to phishing attempts to obtain a user's credentials or other sensitive user input.
In the Versioned Files module through 2.0.3 for SilverStripe 3.x, unpublished versions of files are publicly exposed to anyone who can guess their URL. This guess could be highly informed by a basic understanding of the symbiote/silverstripe-versionedfiles source code. (Users who upgrade from SilverStripe 3.x to 4.x and had Versioned Files installed have no further need for this module, because the 4.x release has built-in versioning. However, nothing in the upgrade process automates the destruction of these insecure artefacts, nor alerts the user to the criticality of destruction.)
SilverStripe through 4.3.3 has incorrect access control for protected files uploaded via Upload::loadIntoFile(). An attacker may be able to guess a filename in silverstripe/assets via the AssetControlExtension.
SQL injection vulnerability in silverstripe/restfulserver module 1.0.x before 1.0.9, 2.0.x before 2.0.4, and 2.1.x before 2.1.2 and silverstripe/registry module 2.1.x before 2.1.1 and 2.2.x before 2.2.1 allows attackers to execute arbitrary SQL commands.