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    CVE-2026-93634

    A cross-account authorization vulnerability in Zimbra Collaboration Suite (ZCS) allows an authenticated user to insert forged shared-file records into another user's mailbox through FileSharedWithMeRequest. The request bypasses delegated-account authorization and accepts attacker-selected file metadata, owner identifiers and declared sizes without validating a corresponding document share. An attacker can plant entries attributed to another real local account without that account sharing a document. No victim interaction is required. ZCS 10.1.16 and 10.1.20 are affected.

    Published:Oct 23, 2026
    Last Modified:Oct 28, 2026
    EPS:Oct 23, 2026
    EPSS Score:0.00221
    CVSS Score:4.3

    Affected Products

    Vendor
    Synacor
    Product
    Zimbra Collaboration Suite
    Vendor
    Zimbra
    Product
    Zimbra Collaboration Suite

    Exploits

    https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/

    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