CVE-2023-39950

efibootguard is a simple UEFI boot loader with support for safely switching
between current and updated partition sets. Insufficient or missing
validation and sanitization of input from untrustworthy bootloader
environment files can cause crashes and probably also code injections into
bg_setenv) or programs using libebgenv. This is triggered when the
affected components try to modify a manipulated environment, in particular
its user variables. Furthermore, bg_printenv may crash over invalid read
accesses or report invalid results. Not affected by this issue is EFI Boot
Guard’s bootloader EFI binary. EFI Boot Guard release v0.15 contains
required patches to sanitize and validate the bootloader environment prior
to processing it in userspace. Its library and tools should be updated, so
should programs statically linked against it. An update of the bootloader
EFI executable is not required. The only way to prevent the issue with an
unpatched EFI Boot Guard version is to avoid accesses to user variables,
specifically modifications to them.