Silverstripe CMS sites through 4.4.4 which have opted into HTTP Cache Headers on responses served by the framework's HTTP layer can be vulnerable to web cache poisoning. Through modifying the X-Original-Url and X-HTTP-Method-Override headers, responses with malicious HTTP headers can return unexpected responses to other consumers of this cached response. Most other headers associated with web cache poisoning are already disabled through request hostname forgery whitelists.

In SilverStripe through 4.5, files uploaded via Forms to folders migrated from Silverstripe CMS 3.x may be put to the default "/Uploads" folder instead. This affects installations which allowed upload folder protection via the optional silverstripe/secureassets module under 3.x. This module is installed and enabled by default on the Common Web Platform (CWP). The vulnerability only affects files uploaded after an upgrade to 4.x.

SilverStripe through 4.3.3 allows a Denial of Service on flush and development URL tools.

In SilverStripe through 4.3.3, the previous fix for SS-2018-007 does not completely mitigate the risk of CSRF in GraphQL mutations,

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In the Versioned Files module through 2.0.3 for SilverStripe 3.x, unpublished versions of files are publicly exposed to anyone who can guess their URL.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.)

In SilverStripe assets 4.0, there is broken access control on files.

In SilverStripe asset-admin 4.0, there is XSS in file titles managed through the CMS.

In SilverStripe through 4.3.3, there is access escalation for CMS users with limited access through permission cache pollution.

SilverStripe through 4.3.3 has Flash Clipboard Reflected XSS.