Critical severity9.8NVD Advisory· Published Sep 1, 2026· Updated Sep 3, 2026
CVE-2026-84637
CVE-2026-84637
Description
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 products
2- Range: <=153.2, <154
Patches
Vulnerability mechanics
References
3- www.mozilla.org/security/advisories/mfsa2026-78/nvdVendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-88/nvdVendor Advisory
- bugzilla.mozilla.org/show_bug.cginvdPermissions Required
News mentions
1- Mozilla Thunderbird: 16 Vulnerabilities Including Critical Sandbox Escapes Disclosed TogetherVypr Intelligence · Sep 1, 2026