CVE-2026-45281
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.28%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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
- CVSS 3.1
- 8.1 HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
- EPSS
- 0.28% probability · 21th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-639
- Affected
- nextcloud/nextcloud server
- Source
- security-advisories@github.com
References
- https://github.com/nextcloud/security-advisories/security/advisories/GHSA-hrrv-mp25-26vvMitigation, Vendor Advisory
- https://github.com/nextcloud/server/pull/59962Issue Tracking, Patch
- https://hackerone.com/reports/3545964Permissions Required
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.