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CVE-2026-45281

HIGHCVSS 8.1/10EPSS 0.28%

Last modified

CVE-2026-45281 is a high-severity vulnerability rated 8.1/10 on the CVSS scale. Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, with the knowledge of other users’ principal URL an attacker could possibly send a request to gain full access to their calendar. EPSS estimates a 0.28% chance of exploitation in the next 30 days.

Description

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, with the knowledge of other users’ principal URL an attacker could possibly send a request to gain full access to their calendar. Therefore, the attacker must be an authenticated user. This is because of improper authorization controls in the backend of the calendar. If the attacker had access to the calendar, they would be able to view and modify it. It is recommended that the Nextcloud Server is upgraded to 33.0.3 or 32.0.9. It is recommended that the Nextcloud Enterprise Server is upgraded to 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, 29.0.16.16, 28.0.14.17, 27.1.11.26, 26.0.13.26, 25.0.13.29, 24.0.12.34, 23.0.12.35, 22.2.10.39, or 21.0.9.23

Metrics

CVSS 3.1
8.1/10

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS Probability
0.28%

20.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
NextcloudNextcloud Server>= 32.0.0, < 32.0.9
NextcloudNextcloud Server>= 33.0.0, < 33.0.3
NextcloudNextcloud Server>= 21.0.0, < 21.0.9.23
NextcloudNextcloud Server>= 22.0.0, < 22.2.10.39
NextcloudNextcloud Server>= 23.0.0, < 23.0.12.35
NextcloudNextcloud Server>= 24.0.0, < 24.0.12.34
NextcloudNextcloud Server>= 25.0.0, < 25.0.13.29
NextcloudNextcloud Server>= 26.0.0, < 26.0.13.26
NextcloudNextcloud Server>= 27.0.0, < 27.1.11.26
NextcloudNextcloud Server>= 28.0.0, < 28.0.14.17
NextcloudNextcloud Server>= 29.0.0, < 29.0.16.16
NextcloudNextcloud Server>= 30.0.0, < 30.0.17.9
NextcloudNextcloud Server>= 31.0.0, < 31.0.14.5

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-45281?
Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, with the knowledge of other users’ principal URL an attacker could possibly send a request to gain full access to their calendar. Therefore, the attacker must be an authenticated user. This is because of improper authorization controls in the backend of the calendar. If the attacker had access to the calendar, they would be able to view and modify it. It is recommended that the Nextcloud Server is upgraded to 33.0.3 or 32.0.9. It is recommended that the Nextcloud Enterprise Server is upgraded to 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, 29.0.16.16, 28.0.14.17, 27.1.11.26, 26.0.13.26, 25.0.13.29, 24.0.12.34, 23.0.12.35, 22.2.10.39, or 21.0.9.23
How severe is CVE-2026-45281?
CVE-2026-45281 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 0.28% probability of exploitation in the next 30 days.
How do I fix CVE-2026-45281?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST