CVE-2025-47793: Nextcloud Server and Groupfolders app vulnerable to bypass of group folder quota limit using attachment in text file

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-05-16 · updated 2026-06-17
Weakness: CWE-770

Description

Nextcloud Server is a self hosted personal cloud system, and the Nextcloud Groupfolders app provides admin-configured folders shared by everyone in a group or team. In Nextcloud Server prior to 30.0.2, 29.0.9, and 28.0.1, Nextcloud Enterprise Server prior to 30.0.2 and 29.0.9, and Nextcloud Groupfolders app prior to 18.0.3, 17.0.5, and 16.0.11, the absence of quota checking on attachments allowed logged-in users to upload files exceeding the group folder quota. Nextcloud Server versions 30.0.2 and 29.0.9, Nextcloud Enterprise Server versions 30.0.2, 29.0.9, or 28.0.12, and Nextcloud Groupfolders app 18.0.3, 17.0.5, and 16.0.11 fix the issue. No known workarounds are available.

Affected products

nextcloud Group Folders: from 16.0.0 before 16.0.11; from 17.0.0 before 17.0.5; from 18.0.0 before 18.0.3 — fixed in 16.0.11, 17.0.5, 18.0.3
Nextcloud Server: from 28.0.0 before 28.0.12; from 29.0.0 before 29.0.9; from 30.0.0 before 30.0.2 — fixed in 28.0.12, 29.0.9, 30.0.2

How to fix

Upgrade to a fixed version: nextcloud Group Folders 16.0.11, 17.0.5, 18.0.3; Nextcloud Server 28.0.12, 29.0.9, 30.0.2. Check the vendor advisory for mitigations.

References

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