CVE-2025-66546

Nextcloud Calendar app allowed booking appointments without the generated token

LOW
3.3
CVSS Score
Published: December 5, 2025 at 04:49 PM UTC
Updated: October 18, 2026 at 02:10 PM UTC
2 products affected across 1 vendorCalendarsecurity-advisories

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Severity
LOW3.3
Exploit prediction
EPSS 0.1%
SSVC
No known exploit

Description

Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.19, 5.5.6, and 6.0.1, the calendar app allowed blindly booking appointments with a squential ID without known the appointment token. This vulnerability is fixed in 4.7.19, 5.5.6, and 6.0.1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

References (4)

x_refsource_MISCIssue Tracking
Source: cverecord
https://github.com/nextcloud/calendar/pull/7537
x_refsource_MISCIssue TrackingVendor Advisory
Source: cverecord
https://hackerone.com/reports/3275810

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

3.3LOWGitHub_M
Attack Vector
LOCAL
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-639

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