Enigmail before 2.0.11 allows PGP signature spoofing: for an inline PGP message, an attacker can cause the product to display a "correctly signed" message indication, but display different unauthenticated text.
Exploitability
AV:NAC:LPR:NUI:NScope
S:UImpact
C:NI:HA:N7.5/CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N