#VU75399 Improper access control in Nextcloud Enterprise Server and Nextcloud Server - CVE-2023-30539

Vulnerability identifier: #VU75399

Vulnerability risk: Medium

CVSSv4.0: 0.4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2023-30539

CWE-ID: CWE-284

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Nextcloud Enterprise Server
Client/Desktop applications / Messaging software
Nextcloud Server
Client/Desktop applications / Messaging software

Vendor: Nextcloud

Description

The vulnerability allows a remote attacker to gain unauthorized access to otherwise restricted functionality.

The vulnerability exists due to improper access restrictions. A remote user can set up workflows using restricted and invisible system tags.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Nextcloud Enterprise Server: 21.0.0 - 25.0.4

Nextcloud Server: 24.0.0 - 25.0.4

---

External links
https://github.com/nextcloud/security-advisories/security/advisories/GHSA-3m2f-v8x7-9w99
https://hackerone.com/reports/1895976
https://github.com/nextcloud/server/pull/37252
https://github.com/nextcloud/files_automatedtagging/pull/705

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.