Multiple security issues have been found in Icedove, Debian’s version of
the Mozilla Thunderbird mail client: Multiple memory safety errors may
lead to the execution of arbitrary code or denial of service.
For the stable distribution (jessie), these problems have been fixed in
version 38.8.0-1~deb8u1.
For the unstable distribution (sid), these problems will be fixed soon.
We recommend that you upgrade your icedove packages.