Thunderbird <=153: Windows Local Exec via File URI Calendar Invites
CVE-2026-84637 Published on September 1, 2026
Calendar invitation attachments could launch local executables
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.
Products Associated with CVE-2026-84637
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Affected Versions
Mozilla Thunderbird:- Version 153.2, <= 153.* is unaffected.
- Version 154, <= * is unaffected.