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.