Peter Hüwe and Hanno Böck discovered that Serendipity, a weblog manager, did not properly sanitise input to several scripts which allowed cross site scripting.
The old stable distribution (sarge) does not contain a serendipity package.
For the stable distribution (etch), this problem has been fixed in version 1.0.4-1+etch1.
For the unstable distribution (sid), this problem has been fixed in version 1.3-1.
We recommend that you upgrade your serendipity package.
MD5 checksums of the listed files are available in the original advisory.