The shim package contains a first-stage UEFI boot loader that handles chaining to a trusted full boot loader under secure boot environments. Security Fix: shim: RCE in http boot support may lead to Secure Boot bypass shim: Interger overflow leads to heap buffer overflow in verify_sbat_section on 32-bits systems shim: Out-of-bounds read printing error messages shim: Out-of-bounds read in verify_buffer_authenticode malformed PE file shim: Out-of-bound read in verify_buffer_sbat shim: out of bounds read when parsing MZ binaries For more details about the security issue, including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page listed in the References section. IMPORTANT: The new shim revokes ALL VERSIONS of GRUB2 before grub2-2.02-0.87.el7_9.14. Therefore GRUB2 MUST be updated to the latest version: grub2-2.02-0.87.el7_9.14 BEFORE or SIMULTANEOUSLY with this shim in order for Secure Boot to continue to work. Failure to update GRUB2 will result in an UNBOOTABLE system.