Horde Kronolith H3 2.1 before 2.1.7 and 2.2 before 2.2-RC2; Nag H3 2.1 before 2.1.4 and 2.2 before 2.2-RC2; Mnemo H3 2.1 before 2.1.2 and H3 2.2 before 2.2-RC2; Groupware 1.0 before 1.0.3 and 1.1 before 1.1-RC2; and Groupware Webmail Edition 1.0 before 1.0.4 and 1.1 before 1.1-RC2 does not validate ownership when performing share changes, which has unknown impact and attack vectors.
https://www.redhat.com/archives/fedora-package-announce/2008-March/msg00176.html
http://www.securityfocus.com/bid/27217
http://secunia.com/advisories/28382
http://lists.horde.org/archives/announce/2008/000377.html
http://lists.horde.org/archives/announce/2008/000376.html
http://lists.horde.org/archives/announce/2008/000371.html
http://lists.horde.org/archives/announce/2008/000369.html
http://lists.horde.org/archives/announce/2008/000368.html
http://lists.horde.org/archives/announce/2008/000366.html
http://lists.horde.org/archives/announce/2008/000365.html
http://lists.horde.org/archives/announce/2008/000364.html