Nextcloud Calendar app used predictable proposal participant tokens_CVE-2025-66511

4.8 / 10

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Description

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.

Basic Information

ID CVE-2025-66511

Source GitHub_M

Published Dec 5, 2025 at 16:42

Modified Dec 5, 2025 at 16:53

Affected Product

Vendor nextcloud

Product security-advisories

Version >= 6.0.0-rc.1, < 6.0.3

Affected Versions nextcloud security-advisories >= 6.0.0-rc.1, < 6.0.3

CWE Classification

CWE-330

References

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    "published": "2025-12-05T16:42:30.236Z",
    "modified": "2025-12-05T16:53:52.674Z",
    "type": "cve",
    "title": "Nextcloud Calendar app used predictable proposal participant tokens",
    "source": "GitHub_M",
    "references": "https://github.com/nextcloud/security-advisories/security/advisories/GHSA-whm3-vv55-gf27\nhttps://github.com/nextcloud/calendar/pull/7659\nhttps://github.com/nextcloud/calendar/commit/8de14ae87f321f5f09280d9895a27d54d24f33fb\nhttps://hackerone.com/reports/3385434",
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