A flaw was found in the way grub2 handled backspace characters entered in username and password prompts. An attacker with access to the system console could use this flaw to bypass grub2 password protection and gain administrative access to the system.
A buffer overflow flaw was found in the way grub2 checked the password entered by the user during bootup. A local attacker could use this flaw to circumvent the password check and, potentially, execute arbitrary code on the system.
Created attachment 1100986 [details]
Here's the fix.
Created grub2 tracking bugs for this issue:
Affects: fedora-all [bug 1290417]
This flaw has been presented at the CCN-CERT conference by the UPV security team:
This issue has been addressed in the following products:
Red Hat Enterprise Linux 7
Via RHSA-2015:2623 https://rhn.redhat.com/errata/RHSA-2015-2623.html
Detailed write-up from the original reporters.