CVE-2025-66511
Medium
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.
SeverityMedium
CVSS4.8
Exploit probability—
Product
Nextcloud Calendar
PublishedDec 5, 2025
First seenDec 5, 2025
Weakness typeCWE-330CWE-330
How to fix
Update
- nextcloud calendar6.0.3 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| nextcloud calendar | 6.0.0 ≤ v < 6.0.3 | 6.0.3 |
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