Vulnerability · Published Dec 5, 2025 · Assigned by GitHub_M
CVE-2025-66550Nextcloud Calendar attachments of local files are offered to downloaded
Medium 5.7
In plain English
A medium-severity security flaw in security-advisories from nextcloud. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities).
Severity (CVSS 3.1)5.7Medium
Exploit odds (30 days)0.4%top 69.4% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| nextcloud | security-advisories | >= 5.0.0-rc.1, < 5.2.4< 4.7.17 |
Weakness: CWE-241 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N
References
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-f29c-ppmv-8mcv x_refsource_CONFIRM
- https://github.com/nextcloud/calendar/pull/6971 x_refsource_MISC
- https://github.com/nextcloud/calendar/commit/63a6c398db01391eb9fd5297a0d4c3d6e614f769 x_refsource_MISC
- https://hackerone.com/reports/3112033 x_refsource_MISC