setpwnam.c in the util-linux package, as included in Red Hat Linux 7.3 and earlier, and other operating systems, does not properly lock a t…

setpwnam.c in the util-linux package, as included in Red Hat Linux 7.3 and earlier, and other operating systems, does not properly lock a temporary file when modifying /etc/passwd, which may allow local users to gain privileges via a complex race condition that uses an open file descriptor in utility programs such as chfn and chsh.