Geary before 0.6.3 does not present the user with a warning when a TLS certificate error is detected, which makes it easier for remote attackers to conduct man-in-the-middle attacks via a crafted certificate.
Weaknesses in this category are related to the design and implementation of data confidentiality and integrity. Frequently these deal with the use of encoding techniques, encryption libraries, and hashing algorithms. The weaknesses in this category could lead to a degradation of the quality data if they are not addressed.