Security researchers from Eclypsium have identified a flaw in grub2 that allows people to access the grub2 prompt, to bypass UEFI secure boot lockdown restrictions and to boot unsigned code. This flaw is tracked by CVE-2020-10713 .
The attack could allow running root-malware to become persistent over booting, e.g. becoming boot-malware, regardless of the operating system.
https://www.suse.com/c/suse-addresses-grub2-secure-boot-issue/ in looking for the patches for each CVE listed locate the patch for SLES11SP4 LTSS.