CVE-2026-84639

Summary

Triggering an error condition in certain MIME bodies would cause uninitialized memory to be used. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

Affected Software

VendorProductVersion RangeStatus
MozillaThunderbird140.15 <= 140.*unaffected
MozillaThunderbird153.2 <= 153.*unaffected
MozillaThunderbird155 <= *unaffected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: partial

References