Mail-0's Zero is an open-source email solution. In version 0.8 it's possible for an attacker to craft an email that executes javascript leading to session hijacking due to improper sanitization. This issue has been patched in version 0.81.
Exploitability
AV:NAC:LAT:NPR:NUI:PVulnerable System
VC:HVI:HVA:NSubsequent System
SC:NSI:NSA:N8.6/CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NOther