USN-871-1 fixed vulnerabilities in KDE. This update provides the corresponding updates for KDE 4.
This update also fixes a directory traversal flaw in KDE when processing help:// URLs. This issue only affected Ubuntu 8.10.
Original advisory details:
It was discovered that the KDE libraries could use KHTML to process an unknown MIME type. If a user or application linked against kdelibs were tricked into opening a crafted file, an attacker could potentially trigger XMLHTTPRequests to remote sites.