The GRUB2's shim_lock verifier allows non-kernel files to be loaded on shim-powered secure boot systems. Allowing such files to be loaded may lead to unverified code and modules to be loaded in GRUB2 breaking the secure boot trust-chain.
https://www.openwall.com/lists/oss-security/2022/06/07/5
https://security.netapp.com/advisory/ntap-20230825-0002/
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-28735