Multiple security issues have been found in Thunderbird which could result in spoofing the displayed sender email address, denial of service or potentially the execution of arbitrary code.
For the oldstable distribution (stretch), these problems have been fixed in version 1:68.8.0-1~deb9u1.
For the stable distribution (buster), these problems have been fixed in version 1:68.8.0-1~deb10u1.
We recommend that you upgrade your thunderbird 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/