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How the Mentioned CVE Works:
This vulnerability is an Insecure Direct Object Reference (IDOR) in the Nextcloud Calendar app. Appointment booking slots are assigned sequential numeric IDs. The application’s endpoint for booking these appointments did not require knowledge of a secure, random appointment token. An attacker could exploit this by systematically enumerating (brute-forcing) these sequential IDs (e.g., /apps/calendar/appointment/1, /apps/calendar/appointment/2, etc.). This allows them to discover and book appointments they were not invited to, without any authentication, leading to unauthorized access and potential disruption of calendar schedules.
DailyCVE Form:
Platform: Nextcloud Calendar
Version: <4.7.19,<5.5.6,<6.0.1
Vulnerability: Blind IDOR
Severity: Under Review
Date: 2025-12-05
Prediction: Patched 2025-12-01
What Undercode Say:
Analytics: grep -r “appointment/book” nextcloud/
Bash Command: for id in {1..1000}; do curl -s “https://target/apps/calendar/appointment/$id” | grep -q “Available” && echo “Found: $id”; done
Code Snippet: Vulnerable endpoint lacked token validation before processing booking logic.
How Exploit:
Attackers brute-force sequential appointment IDs via web requests to book or view slots without authorization.
Protection from this CVE:
Update to versions 4.7.19, 5.5.6, or 6.0.1 immediately.
Impact:
Unauthorized appointment booking, schedule disruption, information disclosure.
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Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
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