modules/xmpp/serv_xmpp.c in Citadel 7.86 and earlier does not properly detect recursion during entity expansion, which allows remote attackers to cause a denial of service (memory and CPU consumption) via a crafted XML document containing a large number of nested entity references, a similar issue to CVE-2003-1564.
code.citadel.org/cgit.cgi/git.citadel.org/commit/?id=27c991cc2059f5530d3d4e9689dc976b745f5b0c
code.citadel.org/cgit.cgi/git.citadel.org/commit/?id=95040add546a705cc2d1d8f16293141f9f9845a6
packages.debian.org/changelogs/pool/main/c/citadel/citadel_7.37-8+lenny1/changelog
packages.debian.org/changelogs/pool/main/c/citadel/citadel_7.83-2squeeze2/changelog
secunia.com/advisories/44788
security.debian.org/debian-security/pool/updates/main/c/citadel/citadel_7.83-2squeeze2.diff.gz
www.debian.org/security/2011/dsa-2250
www.securityfocus.com/bid/48071