If you have a use case which requires the guest session, you can manually re-enable it by writing the following contents to /etc/lightdm/lightdm.conf:
# Manually enable guest sessions despite them not being confined
# IMPORTANT: Makes the system vulnerable to CVE-2017-8900
# https://bugs.launchpad.net/bugs/1663157
[Seat:*]
allow-guest=true
If you have a use case which requires the guest session, you can manually re-enable it by writing the following contents to /etc/lightdm/ lightdm. conf:
# Manually enable guest sessions despite them not being confined /bugs.launchpad .net/bugs/ 1663157
# IMPORTANT: Makes the system vulnerable to CVE-2017-8900
# https:/
[Seat:*]
allow-guest=true