Multiple security issues have been found in Thunderbird, which may lead to the execution of arbitrary code or denial of service.
For the oldstable distribution (jessie), these problems have been fixed in version 52.3.0-4~deb8u2.
For the stable distribution (stretch), these problems have been fixed in version 52.3.0-4~deb9u1.
We recommend that you upgrade your icedove 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/