CVE-2026-45286Nextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint
Updated under an hour ago ()
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It affects nextcloud security-advisories and 1 other product. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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Free account, 1 product
Nextcloud is an open source content collaboration platform. From versions 5.5.13 to before 5.5.17, and 6.2.0 to before 6.2.3, an authenticated user can enumerate users on the same Nextcloud instance by using the Calendar app's endpoint for suggesting attendees. The sharing restrictions, applied to other endpoints, were not effective here. This issue has been patched in versions 5.5.17 and 6.2.3.
- CVSS
- 4.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
- Weakness (CWE)
- CWE-200
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Analyzed
- Record last updated
- Jun 1, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
nextcloud security-advisories nextcloud:security_advisories (from the name) | from 5.5.13, < 5.5.17; from 6.2.0, < 6.2.3 | CNA record |
nextcloud calendar nextcloud:calendar | from 5.5.13 before 5.5.17; from 6.2.0 before 6.2.3 | NVD |
References
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-r697-74m9-gvf2x-refsource-confirm, mitigation, vendor-advisory
- https://github.com/nextcloud/calendar/issues/7971x-refsource-misc, exploit, issue-tracking, patch
- https://github.com/nextcloud/calendar/pull/8197x-refsource-misc, issue-tracking, patch
- https://hackerone.com/reports/3540663x-refsource-misc, permissions-required
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.