Multiple security issues were discovered in Thunderbird, which could result in the execution of arbitrary code or information disclosure. In adddition a number of security issues were addressed in the OpenPGP support.
For the stable distribution (buster), these problems have been fixed in version 1:78.10.0-1~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/