The expat XML parser in the apr_xml_* interface in xml/apr_xml.c in Apache APR-util before 1.3.7 as used in the mod_dav and mod_dav_svn modules in the Apache HTTP Server allows remote attackers to cause a denial of service (memory consumption) via a crafted XML document containing a large number of nested entity references as demonstrated by a PROPFIND request a similar issue to CVE-2003-1564.