In TYPO3 CMS 9.0.0 through 9.5.16 and 10.0.0 through 10.4.1, it has been discovered that backend user settings (in $BE_USER->uc) are vulnerable to insecure deserialization. In combination with vulnerabilities of third party components, this can lead to remote code execution. A valid backend user account is needed to exploit this vulnerability. This has been fixed in 9.5.17 and 10.4.2.

In TYPO3 CMS greater than or equal to 9.5.12 and less than 9.5.17, and greater than or equal to 10.2.0 and less than 10.4.2, it has been discovered that link tags generated by typolink functionality are vulnerable to cross-site scripting; properties being assigned as HTML attributes have not been parsed correctly. This has been fixed in 9.5.17 and 10.4.2.

In TYPO3 CMS greater than or equal to 9.0.0 and less than 9.5.17 and greater than or equal to 10.0.0 and less than 10.4.2, it has been discovered that HTML placeholder attributes containing data of other database records are vulnerable to cross-site scripting. A valid backend user account is needed to exploit this vulnerability. This has been fixed in 9.5.17 and 10.4.2.

In TYPO3 CMS versions 10.4.0 and 10.4.1, it has been discovered that time-based attacks can be used with the password reset functionality for backend users. This allows an attacker to mount user enumeration based on email addresses assigned to backend user accounts. This has been fixed in 10.4.2.

The SVG Sanitizer extension for TYPO3 has a cross-site scripting vulnerability in versions before 1.0.3. Slightly invalid or incomplete SVG markup is not correctly processed and thus not sanitized at all. Albeit the markup is not valid it still is evaluated in browsers and leads to cross-site scripting. This is fixed in version 1.0.3.

An issue was discovered in TYPO3 before 8.7.30, 9.x before 9.5.12, and 10.x before 10.2.2. It has been discovered that the classes QueryGenerator and QueryView are vulnerable to insecure deserialization. One exploitable scenario requires having the system extension ext:lowlevel (Backend Module: DB Check) installed, with a valid backend user who has administrator privileges. The other exploitable scenario requires having the system extension ext:sys_action installed, with a valid backend user who has limited privileges.

An issue was discovered in TYPO3 before 8.7.30, 9.x before 9.5.12, and 10.x before 10.2.2. It has been discovered that the extraction of manually uploaded ZIP archives in Extension Manager is vulnerable to directory traversal. Admin privileges are required in order to exploit this vulnerability. (In v9 LTS and later, System Maintainer privileges are also required.)

An issue was discovered in TYPO3 before 8.7.30, 9.x before 9.5.12, and 10.x before 10.2.2. Because escaping of user-submitted content is mishandled, the class QueryGenerator is vulnerable to SQL injection. Exploitation requires having the system extension ext:lowlevel installed, and a valid backend user who has administrator privileges.

It was found that Typo3 Core versions 4.5.0 - 4.5.5 uses prepared statements that, if the parameter values are not properly replaced, could lead to a SQL Injection vulnerability. This issue can only be exploited if two or more parameters are bound to the query and at least two come from user input.

Cross-site Scripting (XSS) in TYPO3 before 4.3.12, 4.4.x before 4.4.9, and 4.5.x before 4.5.4 allows remote attackers to inject arbitrary web script or HTML via the tcemain flash message.