CVE-2026-45281

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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\u2019 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"}, {"lang": "es", "value": "Nextcloud es una plataforma de colaboraci\u00f3n de contenido de c\u00f3digo abierto. En Nextcloud Server desde las versiones 32.0.0 hasta antes de la 32.0.9, y 33.0.0 hasta antes de la 33.0.3, con el conocimiento de la URL principal de otros usuarios, un atacante podr\u00eda posiblemente enviar una solicitud para obtener acceso completo a su calendario. Por lo tanto, el atacante debe ser un usuario autenticado. Esto se debe a controles de autorizaci\u00f3n inadecuados en el backend del calendario. Si el atacante tuviera acceso al calendario, podr\u00eda verlo y modificarlo. Se recomienda que el Nextcloud Server se actualice a 33.0.3 o 32.0.9. Se recomienda que el Nextcloud Enterprise Server se actualice a 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, o 21.0.9.23."}], "id": "CVE-2026-45281", "lastModified": "2026-07-22T07:10:00.107", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 8.1, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.2, "source": "security-advisories@github.com", "type": "Secondary"}], "ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-45281", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "total"}], "role": "CISA Coordinator", "timestamp": "2026-06-01T19:22:37.089766Z", "version": "2.0.3"}}]}, "published": "2026-06-01T19:16:50.193", "references": [{"source": "security-advisories@github.com", "tags": ["Mitigation", "Vendor Advisory"], "url": "https://github.com/nextcloud/security-advisories/security/advisories/GHSA-hrrv-mp25-26vv"}, {"source": "security-advisories@github.com", "tags": ["Issue Tracking", "Patch"], "url": "https://github.com/nextcloud/server/pull/59962"}, {"source": "security-advisories@github.com", "tags": ["Permissions Required"], "url": "https://hackerone.com/reports/3545964"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-639"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

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