How severe is CVE-2026-45286?

CVE-2026-45286 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2026-45286 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-45286?

CVE-2026-45286 affects Nextcloud Calendar. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-45286?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-45286 have an EU (EUVD) identifier?

Yes. CVE-2026-45286 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-33711.

When was CVE-2026-45286 published?

CVE-2026-45286 was published on 2026-06-01 and last updated on 2026-06-17.

CVE-2026-45286

CVE-2026-45286 is a medium-severity vulnerability in Nextcloud Calendar with a CVSS 3.x base score of 4.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-200.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 0% (20th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-33711
Weakness: CWE-200
Affected product: Nextcloud Calendar
Published: 2026-06-01
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-45286?: 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.
How severe is CVE-2026-45286?: CVE-2026-45286 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2026-45286 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-45286?: CVE-2026-45286 affects Nextcloud Calendar. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-45286?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-45286 have an EU (EUVD) identifier?: Yes. CVE-2026-45286 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-33711.
When was CVE-2026-45286 published?: CVE-2026-45286 was published on 2026-06-01 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nextcloud:calendar:*:*:*:*:*:*:*:*

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