TYPO3 Cross-Site Scripting in Frontend User Login
Date: 2024-06
Affected: composer/typo3/cms, composer/typo3/cms, composer/typo3/cms
Attack vector: xss
Category: vulnerability-disclosure
Severity: Medium
CWE: CWE-79
CVSS: 5.4 (CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N)

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 - <!--###USERNAME###--> for regular frontend rendering (pattern can be defined individually using TypoScript setting config.USERNAME_substToken)


Mitigations:

Architectural layers (MAESTRO):