Nextcloud Calendar up to 4.7.18/5.5.5/6.0.0 authorization

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
3.2$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, was found in Nextcloud Calendar up to 4.7.18/5.5.5/6.0.0. This affects an unknown function. The manipulation results in authorization. This vulnerability was named CVE-2025-66546. The attack needs to be approached locally. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Nextcloud Calendar up to 4.7.18/5.5.5/6.0.0. It has been classified as problematic. Affected is some unknown functionality. The manipulation with an unknown input leads to a authorization vulnerability. CWE is classifying the issue as CWE-639. The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. This is going to have an impact on confidentiality. CVE summarizes:

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.

The advisory is available at github.com. This vulnerability is traded as CVE-2025-66546 since 12/04/2025. The exploitability is told to be easy. Local access is required to approach this attack. The technical details are unknown and an exploit is not available.

Upgrading to version 4.7.19, 5.5.6 or 6.0.1 eliminates this vulnerability.

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Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 3.3
VulDB Meta Temp Score: 3.2

VulDB Base Score: 3.3
VulDB Temp Score: 3.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 3.3
CNA Vector (GitHub_M): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Authorization
CWE: CWE-639 / CWE-285 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: No

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Calendar 4.7.19/5.5.6/6.0.1

Timelineinfo

12/04/2025 CVE reserved
12/05/2025 +1 days Advisory disclosed
12/05/2025 +0 days VulDB entry created
12/05/2025 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CVE: CVE-2025-66546 (🔒)
GCVE (CVE): GCVE-0-2025-66546
GCVE (VulDB): GCVE-100-334518

Entryinfo

Created: 12/05/2025 18:00
Changes: 12/05/2025 18:00 (63)
Complete: 🔍
Cache ID: 216::103

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