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    CVE-2025-66511

    Nextcloud Calendar is a calendar app for Nextcloud. Prior to 6.0.3, the Calendar app generates participant tokens for meeting proposals using a hash function, allowing an attacker to compute valid participant tokens, which allowed them to request details and submit dates in meeting proposals. The tokens are not purely random generated. This vulnerability is fixed in 6.0.3.

    Published:Dec 5, 2025
    Last Modified:Dec 10, 2025
    EPS:Dec 5, 2025
    EPSS Score:0.00017
    CVSS Score:4.8

    Affected Products

    Vendor
    Nextcloud
    Product
    Calendar

    Exploits

    No exploit reference

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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