#git

Due to missing file extensions in $GLOBALS['TYPO3_CONF_VARS']['BE'][‘fileDenyPattern’], backend users are allowed to upload *.phar, *.shtml, *.pl or *.cgi files which can be executed in certain web server setups. A valid backend user account is needed in order to exploit this vulnerability. Derivatives of Debian GNU Linux are handling *.phar files as PHP applications since PHP 7.1 (for unofficial packages) and PHP 7.2 (for official packages). The file extension *.shtml is bound to server side includes which are not enabled per default in most common Linux based distributions. File extension *.pl and *.cgi require additional handlers to be configured which is also not the case in most common distributions (except for /cgi-bin/ location).

TYPO3’s built-in record registration functionality (aka `basic shopping cart`) using recs URL parameters is vulnerable to denial of service. Failing to properly ensure that anonymous user sessions are valid, attackers can use this vulnerability in order to create an arbitrary amount of individual session-data records in the database.

It has been discovered that mechanisms used for configuration of RequireJS package loading are susceptible to information disclosure. This way a potential attack can retrieve additional information about installed system and third party extensions.

It has been discovered that the output of field validation errors in the Form Framework is vulnerable to cross-site scripting.

Failing to properly encode user input, frontend forms handled by the form framework (system extension “form”) are vulnerable to cross-site scripting.

When using the TYPO3 backend in order to create new backend user accounts, database records containing insecure or empty credentials might be persisted. When the type of user account is changed - which might be entity type or the admin flag for backend users - the backend form is reloaded in order to reflect changed configuration possibilities. However, this leads to persisting the current state as well, which can result into some of the following: - account contains empty login credentials (username and/or password) - account is incomplete and contains weak credentials (username and/or password) Albeit the functionality provided by the TYPO3 core cannot be used either with empty usernames or empty passwords, it still can be a severe vulnerability to custom authentication service implementations. This weakness cannot be directly exploited and requires interaction on purpose by some backend user having according privileges.

It has been discovered that `t3://` URL handling and typolink functionality are vulnerable to cross-site scripting. Not only regular backend forms are affected but also frontend extensions which use the rendering with typolink.

It has been discovered that backend users having limited access to specific languages are capable of modifying and creating pages in the default language which actually should be disallowed. A valid backend user account is needed in order to exploit this vulnerability.

It has been discovered that the output table listing in the “Files” backend module is vulnerable to cross-site scripting when a file extension contains malicious sequences. Access to the file system of the server - either directly or through synchronization - is required to exploit the vulnerability.

Failing to properly encode user input, templates using built-in Fluid ViewHelpers are vulnerable to cross-site scripting.