CVE-2025-66546

3.3 LOW 0.1% exploit odds Fix listed Auth & access

What it is

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.

At a glance

Exploitability: Can be exploited locally on the machine with a low-privilege account. Limited direct impact.
Exploit odds: 0.1% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2025-12-05 17:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-18 14:10 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.1% in the next 30 days (EPSS).
Severity: 3.3 LOW (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2025-12-05 17:16 UTC
Last modified: 2026-10-18 14:10 UTC
Exploit probability: 0.1% · EPSS, next 30 days
Weakness: CWE-639 · Insecure direct object reference
Record status: Analyzed

Affected

Nextcloud Calendar < 4.7.19
Nextcloud Calendar < 5.5.6
Nextcloud Calendar 6.0.0

Attack profile CVSS 3.1 · 3.3

Attack vector: Local
Complexity: Low
Privileges needed: Low
User interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: None

Raw vector

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

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2025-66546.md and follow it. Check whether this project is affected by CVE-2025-66546. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record