CVE-2026-84637: mozilla thunderbird

CVSS 9.8 (critical) · published 2026-09-01

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 (NVD): mozilla thunderbird

Fixed in (NVD): 153.2.0, 155.0

Weakness: CWE-434

Source: NVD CVE-2026-84637

References

• https://bugzilla.mozilla.org/show_bug.cgi?id=2043878
• https://www.mozilla.org/security/advisories/mfsa2026-78/
• https://www.mozilla.org/security/advisories/mfsa2026-88/

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