An incorrect implementation of "XEP-0280: Message Carbons" in multiple XMPP clients allows a remote attacker to impersonate any user, including contacts, in the vulnerable application's display. This allows for various kinds of social engineering attacks. This CVE is for ChatSecure (3.2.0 - 4.0.0; only iOS) and Zom (all versions up to 1.0.11; only iOS).