Several issues were discovered in libytnef, a library used to decode application/ms-tnef e-mail attachments. Multiple heap overflows, out-of-bound writes and reads, NULL pointer dereferences and infinite loops could be exploited by tricking a user into opening a maliciously crafted winmail.dat file.
For the stable distribution (jessie), these problems have been fixed in version 1.5-6+deb8u1.
For the upcoming stable (stretch) and unstable (sid) distributions, these problems have been fixed in version 1.9.2-1.
We recommend that you upgrade your libytnef packages.
Further information about Debian Security Advisories, how to apply these updates to your system and frequently asked questions can be found at: https://www.debian.org/security/