MySQL 4.x before 4.0.21, and 3.x before 3.23.49, allows attackers to cause a denial of service (crash or hang) via multiple threads that simultaneously alter MERGE table UNIONs.Referenceshttp://lists.mysql.com/internals/16174http://www.redhat.com/support/errata/RHSA-2004-611.htmlhttp://secunia.com/advisories/12783/http://www.debian.org/security/2004/dsa-562http://marc.info/?l=bugtraq&m=110140517515735&w=2http://lists.mysql.com/internals/16173https://exchange.xforce.ibmcloud.com/vulnerabilities/17667http://sunsolve.sun.com/search/document.do?assetkey=1-26-101864-1http://www.securityfocus.com/bid/11357http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000892http://www.redhat.com/support/errata/RHSA-2004-597.htmlhttp://www.ciac.org/ciac/bulletins/p-018.shtmlhttp://lists.mysql.com/internals/16168http://www.gentoo.org/security/en/glsa/glsa-200410-22.xmlhttp://www.trustix.org/errata/2004/0054/http://bugs.mysql.com/2408http://securitytracker.com/id?1011606http://mysql.bkbits.net:8080/mysql-3.23/diffs/myisammrg/myrg_open.c%401.15