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Vulnerability record · CVE-2023-39958 · published 10 August 2023

CVE-2023-39958: Nextcloud server improper restriction of authentication attempts vulnerability

Nextcloud · Nextcloud Server

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 22.0.0 and prior to versions 22.2.10.13, 23.0.12.8, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1, missing protection allows an attacker to brute force the client secrets of configured OAuth2 clients. Nextcloud Server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 22.2.10.13, 23.0.12.8, 24.0.12.5, 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 0.71% · top 48.3% CWE-307 · Improper restriction of authentication attempts
5.3CVSS 3.1 base score
0.71%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References
17 Jun 2026Last modified by NVD

Description

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 22.0.0 and prior to versions 22.2.10.13, 23.0.12.8, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1, missing protection allows an attacker to brute force the client secrets of configured OAuth2 clients. Nextcloud Server versions 25.0.9, 26.0.4, and 27.0.1 and Nextcloud Enterprise Server versions 22.2.10.13, 23.0.12.8, 24.0.12.5, 25.0.9, 26.0.4, and 27.0.1 contain a patch for this issue. No known workarounds are available.

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.

References

LinkTags
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-vv27-g2hq-v48h Vendor Advisory
https://github.com/nextcloud/server/pull/38773 PatchVendor Advisory
https://hackerone.com/reports/1258448 Third Party Advisory
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-vv27-g2hq-v48h Vendor Advisory
https://github.com/nextcloud/server/pull/38773 PatchVendor Advisory
https://hackerone.com/reports/1258448 Third Party Advisory

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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-2023-39958), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.