A flaw was found in the grub2-set-bootflag utility of grub2. When the utility is run under resource pressure (by setting RLIMIT), it can cause grub2 config files to be truncated leaving the system non-bootable on subsequent reboots.
Name: Tavis Ormandy
grub-set-bootflag is a command line to set bootflags in GRUB's stored environment. This is a downstream utility which is shipped with Red Hat Enterprise Linux 8 and Fedora. A flaw was found in this application which would could allow a local attacker (someone having a local account on the system) to cause grub configuration files to be truncated. Whenever the machine was rebooted, grub would fail to read the configuration files and the system would be rendered unbootable.
Remove the "grub-set-bootflag" from the system, by manually the deleting the binary file. Note: On subsequent updates of the "grub2-tools-minimal" rpm, the file will be re-installed.
Created attachment 1639336 [details]
Created attachment 1639337 [details]
Created grub2 tracking bugs for this issue:
Affects: fedora-all [bug 1776580]
This issue has been addressed in the following products:
Red Hat Enterprise Linux 8
Via RHSA-2020:0335 https://access.redhat.com/errata/RHSA-2020:0335
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):