CVE 2017-5593
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 Psi+ (0.16.563.580 - 0.16.571.627).
See the 
CVE page on Mitre.org
for more details.
