A bug has been discovered in several packages that execute the setuid() system call without checking for success when trying to drop privileges, which may fail with some PAM configurations.
For the stable distribution (sarge) this problem has been fixed in version 4.0.3-31sarge8.
For the unstable distribution (sid) this problem has been fixed in version 4.0.17-2.
We recommend that you upgrade your passwd package.
MD5 checksums of the listed files are available in the original advisory.