An issue was discovered in Enigmail before 1.9.9 that allows remote attackers to trigger use of an intended public key for encryption, because incorrect regular expressions are used for extraction of an e-mail address from a comma-separated list, as demonstrated by a modified Full Name field and a homograph attack, aka TBE-01-002.
https://www.mail-archive.com/enigmail-users%40enigmail.net/msg04280.html
https://www.debian.org/security/2017/dsa-4070
https://lists.debian.org/debian-security-announce/2017/msg00333.html
https://lists.debian.org/debian-lts-announce/2017/12/msg00021.html
https://enigmail.net/download/other/Enigmail%20Pentest%20Report%20by%20Cure53%20-%20Excerpt.pdf