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CVE-2025-66550
Nextcloud Calendar attachments of local files are offered to downloaded
Medium5.7EPSS 0.37%
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium5.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N |
| NVDNVD · Analyzed | 3.1 | Medium5.7 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:N |
- EPSS (exploitation in 30 days)
- 0.37% · top 69% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.7.
Weakness
Affected products
nextcloud · security-advisories
- affected >= 5.0.0-rc.1, < 5.2.4
- affected < 4.7.17
References (4)
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-f29c-ppmv-8mcv (opens in a new tab)x_refsource_CONFIRM
- https://github.com/nextcloud/calendar/pull/6971 (opens in a new tab)x_refsource_MISC
- https://github.com/nextcloud/calendar/commit/63a6c398db01391eb9fd5297a0d4c3d6e614f769 (opens in a new tab)x_refsource_MISC
- https://hackerone.com/reports/3112033 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2025-66550)Record last updated .