The Apache HTTP Server is a popular Web server. The httpd package shipped with Red Hat Enterprise Linux 3 contains embedded copies of the Apache Portable Runtime libraries, which provide a free library of C data structures and routines, and also additional utility interfaces to support XML parsing, LDAP, database interfaces, URI parsing, and more. Multiple integer overflow flaws, leading to heap-based buffer overflows, were found in the way the Apache Portable Runtime manages memory pool and relocatable memory allocations. An attacker could use these flaws to issue a specially-crafted request for memory allocation, which would lead to a denial of service or, potentially, execute arbitrary code with the privileges of an application using the APR libraries. A denial of service flaw was found in the Apache mod_deflate module. This module continued to compress large files until compression was complete, even if the network connection that requested the content was closed before compression completed. This would cause mod_deflate to consume large amounts of CPU if mod_deflate was enabled for a large file. This update also fixes the following bug: * in some cases the Content-Length header was dropped from HEAD responses. This resulted in certain sites not working correctly with mod_proxy, such as www.windowsupdate.com. All httpd users should upgrade to these updated packages, which contain backported patches to correct these issues. After installing the updated packages, the httpd daemon must be restarted for the update to take effect.