Stefan Esser discovered a vulnerability in the XML-RPC libraries which are also present in egroupware, a web-based groupware suite, that allows injection of arbitrary PHP code into eval() statements.
The old stable distribution (woody) does not contain egroupware packages.
For the stable distribution (sarge) this problem has been fixed in version 1.0.0.007-2.dfsg-2sarge2.
For the unstable distribution (sid) this problem has been fixed in version 1.0.0.009.dfsg-1.
We recommend that you upgrade your egroupware packages.