Medium 5.7Published Dec 5, 2025

CVE-2025-66550Nextcloud Calendar is a calendar app for Nextcloud.

Updated under an hour ago (2026-10-19 07:10 UTC)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for nextcloud calendar

Exploited in the last 30 days

Nextcloud Calendar is a calendar app for Nextcloud. Prior to 4.7.17 and 5.2.4, when a malicious user creates a calendar event with a crafted attachment that links to a download link of a file on the same Nextcloud server, the file would be downloaded without the user confirming the action. This vulnerability is fixed in 4.7.17 and 5.2.4.

CVSS: 5.7 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N
Weakness (CWE): CWE-241
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Not given
NVD analysis: Analyzed
Record last updated: Oct 18, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

nextcloud calendar nextcloud:calendar	from 4.0.0 before 4.7.17; from 5.0.0 before 5.2.4	NVD

References

https://github.com/nextcloud/calendar/commit/63a6c398db01391eb9fd5297a0d4c3d6e614f769patch
https://github.com/nextcloud/calendar/pull/6971issue-tracking
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-f29c-ppmv-8mcvpatch, vendor-advisory
https://hackerone.com/reports/3112033issue-tracking, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.