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    CVE-2026-84639

    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.

    Published:Sep 1, 2026
    Last Modified:Sep 3, 2026
    EPS:Sep 1, 2026
    EPSS Score:0.00344
    CVSS Score:9.1

    Affected Products

    Vendor
    Mozilla
    Product
    Thunderbird

    Exploits

    No exploit reference

    Common Weakness Enumeration

    CWE-457 Use of Uninitialized Variable

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

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    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High