CVE-2025-66511 - CVE House
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Status published Medium CVE-2025-66511

Nextcloud Calendar app used predictable proposal participant tokens

Vulnerability 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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

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Credits & Attribution

No credits recorded in the NVD database.

References

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Affected Vendor

Affected Software

security-advisories
Vulnerable Versions:
>= 6.0.0-rc.1, < 6.0.3

Timeline

Official Publish: December 5th, 2025
Last Modified: December 5th, 2025
Added to House: July 22nd, 2026

CVSS Vectors

V3: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

Weaknesses (CWE)

CWE-330

MITRE ATT&CK TTPs

No associated TTPs found for this vulnerability.