From release notes:
This version resolves the following CVEs:
* CVE-2017-9470
* CVE-2017-9471
* CVE-2017-9474
* CVE-2017-9058
* CVE-2017-12142
* CVE-2017-12141
* CVE-2017-12144
ytnef, programs that use libytnef to parse and handle Microsoft TNEF
attachments.
These are the programs that come with the same distfile as libytnef
and are from the same author.