by Kastro
Paper/Archive/CVE-2026-84637

CVE-2026-84637

Mozilla Thunderbird — Calendar invitation attachments could launch local executables

EPSS 0.6%CVSS 9.8
critical.is priorityof 100
39
CVSS 9.8 (ADP)9.8 / 10 × 3029.4Not in CISA KEV+300.0EPSS percentile 50.0.500 × 2010.0No public exploit+100.0SSVC exploitation: none+100.0
Description · from the CVE record

Malicious calendar invitations could use file URI attachments to launch local or network-hosted executables on Windows, bypassing Thunderbird's normal executable attachment protections. With the new invitation display enabled, the attachment could also appear under a misleading filename. This vulnerability was fixed in Thunderbird 154 and Thunderbird 153.2.

Affected

ProductAffectedFixed inSource
Thunderbirdsee advisory153.2CNA

Scores by source

CISA ADP9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADPSSVCExploitation: none · Automatable: yes · Technical impact: total

References

refbugzilla.mozilla.org/show_bug.cgi?id=2043878refmozilla.org/security/advisories/mfsa2026-78refmozilla.org/security/advisories/mfsa2026-88