Nextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint
Published Jun 1, 2026
4.3
MEDIUMCVSS 3.1
EPSS 0.46%
Description
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.
Affected products
-
Affected
- ≥ 5.5.13, < 5.5.17
- ≥ 6.2.0, < 6.2.3
Default status is the baseline for the product. Each version can override it (patched versions can be marked unaffected).
| Vendor | Product | Default status | Versions |
|---|---|---|---|
| Nextcloud | Security-Advisories | unknown | Affected
|
No data.
No Red Hat product state for this CVE.
No package ranges for this CVE.
Remediation
No remediation recorded yet.
References (5)
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-33711 Advisory
- https://github.com/nextcloud/calendar/issues/7971 x_refsource_MISCExploitIssue TrackingPatch
- https://github.com/nextcloud/calendar/pull/8197 x_refsource_MISCIssue TrackingPatch
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-r697-74m9-gvf2 x_refsource_CONFIRMMitigationVendor Advisory
- https://hackerone.com/reports/3540663 x_refsource_MISCPermissions Required
| Link | Providers | Tags |
|---|---|---|
| https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-33711 | Advisory | |
| https://github.com/nextcloud/calendar/issues/7971 | x_refsource_MISCExploitIssue TrackingPatch | |
| https://github.com/nextcloud/calendar/pull/8197 | x_refsource_MISCIssue TrackingPatch | |
| https://github.com/nextcloud/security-advisories/security/advisories/GHSA-r697-74m9-gvf2 | x_refsource_CONFIRMMitigationVendor Advisory | |
| https://hackerone.com/reports/3540663 | x_refsource_MISCPermissions Required |
Change history (0)
No recorded changes yet.
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GitHub
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