The _bfd_XX_bfd_copy_private_bfd_data_common function in peXXigen.c in the Binary File Descriptor (BFD) library (aka libbfd), as distributed in GNU Binutils 2.30, processes a negative Data Directory size with an unbounded loop that increases the value of (external_IMAGE_DEBUG_DIRECTORY) *edd so that the address exceeds its own memory region, resulting in an out-of-bounds memory write, as demonstrated by objcopy copying private info with _bfd_pex64_bfd_copy_private_bfd_data_common in pex64igen.c.