Mozilla Thunderbird is a standalone mail and newsgroup client. This update upgrades Thunderbird to version 91.2.0. Security Fix(es): * Mozilla: Use-after-free in MessageTask (CVE-2021-38496) * Mozilla: Memory safety bugs fixed in Firefox 93, Firefox ESR 78.15, and Firefox ESR 91.2 (CVE-2021-38500) * Mozilla: Memory safety bugs fixed in Firefox 93 and Firefox ESR 91.2 (CVE-2021-38501) * Mozilla: Downgrade attack on SMTP STARTTLS connections (CVE-2021-38502) * rust-crossbeam-deque: race condition may lead to double free (CVE-2021-32810) * Mozilla: Validation message could have been overlaid on another origin (CVE-2021-38497) * Mozilla: Use-after-free of nsLanguageAtomService object (CVE-2021-38498) 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.