An issue was discovered in the selinux-policy (aka Reference Policy) package 3.14 through 2020-08-24 because the .config/Yubico directory is mishandled. Consequently, when SELinux is in enforced mode, pam-u2f is not allowed to read the user’s U2F configuration file. If configured with the nouserok option (the default when configured by the authselect tool), and that file cannot be read, the second factor is disabled. An attacker with only the knowledge of the password can then log in, bypassing 2FA.

Mitigation

To manually permit the read of the config file, the file's SELinux context can be modified :
For example, for a given user '<USER>' :

chcon -R -t auth_home_t ~<USER>/.config/Yubico