Uninitialized memory in MIME parsing. (CVE-2026-84639) One byte overflow read in mail parser. (CVE-2026-84640) Information disclosure due to malicious IMAP server response. (CVE-2026-84641) Calendar invitation attachments could launch local executables. (CVE-2026-84637) Allowed UNC hostnames for attachments interpreted as a regular expression. (CVE-2026-84642) Sandbox escape in the Remote Settings Client component. (CVE-2026-75874) Privilege escalation in the DOM: Workers component. (CVE-2026-16365) Use-after-free in the JavaScript: GC component. (CVE-2026-84118) Sandbox escape due to use-after-free in the DOM: Navigation component. (CVE-2026-84119) Use-after-free in the Audio/Video component. (CVE-2026-84120) Sandbox escape due to use-after-free in the DOM: Security component. (CVE-2026-84121) Use-after-free in the Audio/Video component. (CVE-2026-84122) Privilege escalation due to use-after-free in the Graphics: WebGPU component. (CVE-2026-84123) Use-after-free in the DOM: Core & HTML component. (CVE-2026-84124) Use-after-free in the DOM: Core & HTML component. (CVE-2026-84125) Privilege escalation in the DOM: Navigation component. (CVE-2026-16371) Privilege escalation in the Application Update component. (CVE-2026-74952) Site isolation issue in the DOM: Navigation component. (CVE-2026-84129) Information disclosure in the Graphics: WebGPU component. (CVE-2026-84130) Privilege escalation due to invalid pointer in the Graphics component. (CVE-2026-84131) Information disclosure in the Networking: HTTP component. (CVE-2026-84132) Site isolation issue in the DOM: Push Subscriptions component. (CVE-2026-84133) Other issue in the Profile Backup component. (CVE-2026-84134) Other issue in the DOM: Navigation component. (CVE-2026-84136) Spoofing issue in the DOM: Core & HTML component. (CVE-2026-84137) Clickjacking issue in the DOM: Events component. (CVE-2026-84139) Site isolation issue in the DOM: Navigation component. (CVE-2026-84140) Integer overflow in the Graphics: ImageLib component. (CVE-2026-84141) Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15. (CVE-2026-84143) Internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2. (CVE-2026-84144) Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15. (CVE-2026-84145)