Mozilla Thunderbird is a standalone mail and newsgroup client. This update upgrades Thunderbird to version 78.12.0. Security Fix(es): * Mozilla: IMAP server responses sent by a MITM prior to STARTTLS could be processed (CVE-2021-29969) * Mozilla: Use-after-free in accessibility features of a document (CVE-2021-29970) * Mozilla: Memory safety bugs fixed in Firefox 90 and Firefox ESR 78.12 (CVE-2021-29976) * chromium-browser: Out of bounds write in ANGLE (CVE-2021-30547) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.