SilverStripe through 4.6.0-rc1 has an XXE Vulnerability in CSSContentParser. A developer utility meant for parsing HTML within unit tests can be vulnerable to XML External Entity (XXE) attacks. When this developer utility is misused for purposes involving external or user submitted data in custom project code, it can lead to vulnerabilities such as XSS on HTML output rendered through this custom code. This is now mitigated by disabling external entities during parsing. (The correct CVE ID year is 2020 [CVE-2020-25817, not CVE-2021-25817]).
SilverStripe 4.5.0 allows attackers to read certain records that should not have been placed into a result set. This affects silverstripe/recipe-cms. The automatic permission-checking mechanism in the silverstripe/graphql module does not provide complete protection against lists that are limited (e.g., through pagination), resulting in records that should have failed a permission check being added to the final result set. GraphQL endpoints are configured by default (e.g., for assets), but the admin/graphql endpoint is access protected by default. This limits the vulnerability to all authenticated users, including those with limited permissions (e.g., where viewing records exposed through admin/graphql requires administrator permissions). However, if custom GraphQL endpoints have been configured for a specific implementation (usually under /graphql), this vulnerability could also be exploited through unauthenticated requests. This vulnerability only applies to reading records; it does not allow unauthorised changing of records.
In SilverStripe through 4.5, malicious users with a valid Silverstripe CMS login (usually CMS access) can craft profile information which can lead to XSS for other users through specially crafted login form URLs.