Paul Szabo discovered that the netkit ftp server switches the user id too late, which may lead to the bypass of access restrictions when running on NFS. This update also adds return value checks to setuid() calls, which may fail in some PAM configurations.
For the stable distribution (sarge) this problem has been fixed in version 0.17-20sarge2.
For the upcoming stable distribution (etch) this problem has been fixed in version 0.17-22.
For the unstable distribution (sid) this problem has been fixed in version 0.17-22.
We recommend that you upgrade your ftpd package.
MD5 checksums of the listed files are available in the original advisory.