Vulnerability record · CVE-2023-39959 · published 10 August 2023

CVE-2023-39959: Nextcloud server improper access control vulnerability

Nextcloud · Nextcloud Server

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.9, 26.0.4, and 27.0.1, unauthenticated users could send a DAV request which reveals whether a calendar or an address book with the given identifier exists for the victim. Nextcloud Server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. No known workarounds are available.

5.3 CVSS 3.1 Medium EPSS 0.61% · top 53.0% CWE-284 · Improper access control

5.3CVSS 3.1 base score

0.61%EPSS exploitation probability, 30 days

NoNot in CISA KEV

1Affected product versions listed by NVD

6References

17 Jun 2026Last modified by NVD

Description

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Nextcloud Server Nextcloud

References

Link	Tags
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-g97r-8ffm-hfpj	Vendor Advisory
https://github.com/nextcloud/server/pull/38747	Patch
https://hackerone.com/reports/1832126	Permissions Required
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-g97r-8ffm-hfpj	Vendor Advisory
https://github.com/nextcloud/server/pull/38747	Patch
https://hackerone.com/reports/1832126	Permissions Required

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2023-39959), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.