TYPO3 Cross-Site Scripting in Frontend User Login

Failing to properly encode user input, login status display is vulnerable to cross-site scripting in the website frontend. A valid user account is needed in order to exploit this vulnerability - either a backend user or a frontend user having the possibility to modify their user profile.

Template patterns that are affected are

• ###FEUSER_[fieldName]### using system extension felogin
• for regular frontend rendering (pattern can be defined individually using TypoScript setting config.USERNAME_substToken)