Paul Szabo discovered bugs in three scripts included in the sendmail package where temporary files were created insecurely (expn, checksendmail and doublebounce.pl). These bugs could allow an attacker to gain the privileges of a user invoking the script (including root).
For the stable distribution (woody) these problems have been fixed in version 8.12.3-6.4.
For the old stable distribution (potato) these problems have been fixed in version 8.9.3-26.1.
For the unstable distribution (sid) these problems have been fixed in version 8.12.9-2.
We recommend that you update your sendmail package.
MD5 checksums of the listed files are available in the original advisory.