CVE-2026-84142criticalCWE-200

CVE-2026-84142: critical vulnerability in Mozilla Thunderbird

Internally found bugs fixed in Thunderbird 155

Published · Updated

Follow this CVE+ Monitor Firefox+ Monitor Thunderbird

E-mail alert when it lands in KEV, gets a public PoC or its score goes up.

28Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 9.8epss 0.6%
Internally found bugs present in Thunderbird 154. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155 and Thunderbird 155.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Affected products
Mozilla · FirefoxMozilla · Thunderbird
Related CVEs — Mozilla Thunderbird

In the same product, most dangerous first.

CVE-2016-9079HIGHCVE-2016-9079EPSS 87.4%KEVCVE-2019-11708CRITICALCVE-2019-11708EPSS 55.9%KEVCVE-2019-17026HIGHCVE-2019-17026EPSS 46.3%KEVCVE-2019-11707HIGHCVE-2019-11707EPSS 38.0%KEVCVE-2024-9680CRITICALCVE-2024-9680EPSS 23.2%KEVCVE-2022-26485HIGHCVE-2022-26485EPSS 14.3%KEV