CVE-2025-66550
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.
Does this matter?
Lower severity and a low EPSS score (0.34%). Track it; it rarely justifies an emergency change on its own.
Description
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 3.1
- 5.7 MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N
- EPSS
- 0.34% probability · 27th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-241
- Affected
- nextcloud/calendar
- Source
- security-advisories@github.com
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.