The Admin Classic Bundle provides a Backend UI for Pimcore. AdminBundle\Security\PimcoreUserTwoFactorCondition introduced in v11 disable the two factor authentication for all non-admin security firewalls. An authenticated user can access the system without having to provide the two factor credentials. This issue has been patched in version 1.2.2.
Exploitability
AV:NAC:LPR:HUI:RScope
S:CImpact
C:HI:HA:H8.4/CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:HOther