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CVE-2025-66546

Nextcloud Calendar app allowed booking appointments without the generated token

Published: Dec 5, 2025Updated: Dec 9, 2025 Sources: CVE List NVD BDUCWE-639
3.3LOW
NVD MITRE
EPSS Score
0.1%
Top 96.6%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
Not available

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.

No summary for this CVE yet.

CVSS Vector Breakdown

AV:LAC:LPR:LUI:NS:UC:LI:NA:N
Exploitability
AV:LAttack Vector
Local
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:LConfidentiality
Low
I:NIntegrity
None
A:NAvailability
None
Open in CVSS calculator →

Weaknesses

CWE-639

Affected Products

nextcloud
oss-project·DEaka nextcloud server
security-advisoriesSaaSSaaS Service
Cloud & SaaS / saas-application
calendarSaaSWeb App
Cloud & SaaS / saas-application
ООО «Ред Софт»
commercial·RUaka red soft
РЕД ОСOn-premOS
Operating Systems / linux-distro
Nextcloud GmbH
commercial·DEaka nextcloud enterprise server, nextcloud calendar, nextcloud server
Nextcloud CalendarSaaS
Cloud & SaaS / saas-application

Exploitability

Official Patch Available

Attack Graph

Products CVE Techniques Tactics

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MITRE ATT&CK

1 technique
Initial Access
View detailed technique mapping

References

https://github.com/nextcloud/calendar/commit/f41650c3681fc4a4130eb883f5c0899c011326b3
github.com
https://github.com/nextcloud/calendar/pull/7537
github.com
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-7x2j-2674-fj95
github.com
and 7 more references View all →

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