A flaw was found in the copying tool `nbdcopy` of libnbd. When performing multi-threaded copies using asynchronous nbd calls, nbdcopy was blindly treating the completion of an asynchronous command as successful, rather than checking the *error parameter. This could result in the silent creation of a corrupted destination image.
https://listman.redhat.com/archives/libguestfs/2022-February/msg00104.html
https://gitlab.com/nbdkit/libnbd/-/commit/8d444b41d09a700c7ee6f9182a649f3f2d325abb
https://bugzilla.redhat.com/show_bug.cgi?id=2050324