Linux · 
Red Hat · Security advisory · September 30, 2026
Red Hat · Security advisory · September 30, 2026RHSA-2026:77631: thunderbird security update
RHSA-2026:77631, released September 30, 2026, fixes 13 CVEs in thunderbird (version 140.15.0-1.el10_0). None of them is reported as exploited. Patch Radar priority: Urgent.
Urgent
CVEs closed
13
5 rated Critical
Exploited
0
None reported
Highest CVSS
10.0
Base score, 0 to 10
Highest EPSS
0.0046
39th percentile
Priority of the 13 CVEs
Patch now 0
Urgent 5
High 8
Routine 0
Fixed package versions
| Product | Release | Fixed in |
|---|---|---|
| thunderbird | RHEL 10 | 140.15.0-1.el10_0 |
CVEs this fix closes
| Priority | CVE | Title | CVSS | EPSS | Exploitation |
|---|---|---|---|---|---|
| Urgent | CVE-2026-75874 | Sandbox escape in the Remote Settings Client component | 10.0 | 0.0046 | 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-2026-84145 | Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15 | 7.5 | 0.0037 | None reported |
| High | CVE-2026-84131 | Privilege escalation due to invalid pointer in the Graphics component | 8.8 | 0.0033 | None reported |
| High | CVE-2026-16365 | Privilege escalation in the DOM: Workers component | 8.8 | 0.0028 | 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-2026-84120 | 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-2026-84124 | Use-after-free in the DOM: Core & HTML component | 8.8 | 0.0017 | None reported |
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