Mozilla Thunderbird 155.0
Mozilla Thunderbird 155.0, released August 28, 2026, fixes 31 CVEs in Mozilla Thunderbird. None of them is reported as exploited. Patch Radar priority: Urgent. The latest Mozilla Thunderbird is 159.0, which also fixes every one of these CVEs.
Superseded. The latest Mozilla Thunderbird is 159.0, which also fixes every CVE on this page. Install that instead.
Priority of the 31 CVEs
Applies to
| Product | Version |
|---|---|
| Mozilla Thunderbird | 155.0 |
CVEs this fix closes
| Priority | CVE | Title | CVSS | EPSS | Exploitation |
|---|---|---|---|---|---|
| Urgent | CVE-2026-84637 | Calendar invitation attachments could launch local executables | 9.8 | 0.0063 | None reported |
| Urgent | CVE-2026-84134 | Other issue in the Profile Backup component | 9.8 | 0.0057 | None reported |
| Urgent | CVE-2026-84142 | Internally found bugs fixed in Thunderbird 155 | 9.8 | 0.0056 | None reported |
| Urgent | CVE-2026-84143 | Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15 | 9.8 | 0.0038 | None reported |
| Urgent | CVE-2026-84639 | Uninitialized memory in MIME parsing | 9.1 | 0.0032 | None reported |
| Urgent | CVE-2026-84119 | Sandbox escape due to use-after-free in the DOM: Navigation component | 9.6 | 0.0032 | None reported |
| Urgent | CVE-2026-84121 | Sandbox escape due to use-after-free in the DOM: Security component | 9.6 | 0.0032 | None reported |
| High | CVE-2026-84130 | Information disclosure in the Graphics: WebGPU component | 7.5 | 0.0044 | None reported |
| High | CVE-2026-84128 | Privilege escalation in the WebDriver BiDi component | 8.8 | 0.0044 | None reported |
| High | CVE-2026-84123 | Privilege escalation due to use-after-free in the Graphics: WebGPU component | 8.8 | 0.0044 | None reported |
| High | CVE-2026-84144 | Internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2 | 7.5 | 0.0043 | None reported |
| High | CVE-2026-84642 | Allowed UNC hostnames for attachments interpreted as a regular expression | 7.5 | 0.0042 | None reported |
| High | CVE-2026-84145 | Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15 | 7.5 | 0.0037 | None reported |
| High | CVE-2026-84141 | Integer overflow in the Graphics: ImageLib component | 9.8 | 0.0034 | None reported |
| High | CVE-2026-84131 | Privilege escalation due to invalid pointer in the Graphics component | 8.8 | 0.0033 | None reported |
| High | CVE-2026-84641 | Information disclosure due to malicious IMAP server response | 7.5 | 0.0027 | None reported |
| High | CVE-2026-84640 | One byte overflow read in mail parser | 7.5 | 0.0026 | None reported |
| High | CVE-2026-84132 | Information disclosure in the Networking: HTTP component | 7.5 | 0.0026 | None reported |
| High | CVE-2026-84120 | Use-after-free in the Audio/Video component | 7.5 | 0.0022 | None reported |
| High | CVE-2026-84122 | Use-after-free in the Audio/Video component | 7.5 | 0.0021 | None reported |
| High | CVE-2026-84129 | Site isolation issue in the DOM: Navigation component | 9.8 | 0.0019 | None reported |
| High | CVE-2026-84133 | Site isolation issue in the DOM: Push Subscriptions component | 9.8 | 0.0019 | None reported |
| High | CVE-2026-84140 | Site isolation issue in the DOM: Navigation component | 9.8 | 0.0018 | None reported |
| High | CVE-2026-84124 | Use-after-free in the DOM: Core & HTML component | 8.8 | 0.0017 | None reported |
| Routine | CVE-2026-84138 | Denial-of-service in the PDF Viewer component | 6.5 | 0.0037 | None reported |
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