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CVE-2026-45286

Nextcloud: Calendar app leaked user identifiers via attendee suggestion endpoint

Published: Jun 1, 2026Updated: Jun 1, 2026 Sources: CVE List NVD
NVD MITRE
4.3CVSS
MEDIUM

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.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:UC:LI:NA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:LConfidentiality
Low
I:NIntegrity
None
A:NAvailability
None

Weaknesses

CWE-200

Affected Products

security-advisories
nextcloud

Attack Graph

Products CVE Techniques Tactics

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Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

MITRE ATT&CK

1 technique
Collection
View detailed technique mapping

References

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-r697-74m9-gvf2
github.com
https://github.com/nextcloud/calendar/issues/7971
github.com
https://github.com/nextcloud/calendar/pull/8197
github.com
and 1 more references View all →

Timeline

Published
Jun 1, 2026
Last Updated
Jun 1, 2026

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