os/linux/elf.rb in Homebrew brew before 4.2.20 uses ldd to load ELF files obtained from untrusted sources, which allows attackers to achieve code execution via an ELF file with a custom .interp section. NOTE: this code execution would occur during an un-sandboxed binary relocation phase, which occurs before a user would expect execution of downloaded package content. (237d1e783f7ee261beaba7d3f6bde22da7148b0a was the tested vulnerable version.)
The product includes web functionality (such as a web widget) from another domain, which causes it to operate within the domain of the product, potentially granting total access and control of the product to the untrusted source.