A vulnerability has been identified in the backend user interface functionality involving deep links, which is susceptible to Cross-Site Request Forgery (CSRF). State-changing actions in downstream components incorrectly accepted submissions via HTTP GET and did not enforce the appropriate HTTP method. Successful exploitation requires the victim to have an active session on the backend user interface and to be deceived into interacting with a malicious URL targeting the backend. This can occur when the user opens a malicious link or visits a compromised website with misconfigured settings, such as the `security.backend.enforceReferrer` feature being disabled or the `BE/cookieSameSite` configuration set to lax or none. The vulnerability in the affected downstream component “Extension Manager Module” allows attackers to retrieve and install 3rd party extensions from the TYPO3 Extension Repository, potentially leading to remote code execution.