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