CVE-2025-47794 in Server
Summary
by MITRE • 05/16/2025
Nextcloud Server is a self hosted personal cloud system. In Nextcloud Server prior to 29.0.13, 30.0.7, and 31.0.1 and Nextcloud Enterprise Server prior to 26.0.13.13, 27.1.11.13, 28.0.14.4, 29.0.13, 30.0.7, and 31.0.1, an attacker on a multi-user system may read temporary files from Nextcloud running with a different user account, or run a symlink attack. Nextcloud Server versions 29.0.13, 30.0.7, and 31.0.1 and Nextcloud Enterprise Server 26.0.13.13, 27.1.11.13, 28.0.14.4, 29.0.13, 30.0.7, and 31.0.1 fix the issue. No known workarounds are available.
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Analysis
by VulDB Data Team • 10/01/2025
This vulnerability affects Nextcloud Server installations running versions prior to specific patched releases, creating a critical security risk in multi-user environments where privilege escalation and information disclosure can occur. The flaw stems from inadequate handling of temporary files within the Nextcloud file management system, allowing attackers to potentially access or manipulate files owned by different user accounts. This represents a significant breakdown in the isolation mechanisms that should protect user data within shared hosting environments.
The technical implementation of this vulnerability involves improper temporary file management that enables attackers to either read temporary files created by other user processes or execute symlink attacks against the Nextcloud service. When Nextcloud operates on multi-user systems, temporary files are often created with predictable naming conventions or in directories with insufficient access controls. Attackers can exploit this by creating symbolic links in strategic locations or by directly accessing temporary file paths that should be restricted to specific user contexts. This vulnerability directly maps to CWE-352, which addresses Cross-Site Request Forgery (CSRF) and related privilege escalation issues in file handling operations.
The operational impact of this vulnerability extends beyond simple information disclosure to potentially enable more sophisticated attacks including privilege escalation and data theft across user boundaries. In enterprise environments where multiple users share the same Nextcloud instance, attackers could gain access to sensitive documents, personal files, or even system-level information that should remain isolated. The attack surface is particularly concerning in shared hosting scenarios or cloud deployments where Nextcloud instances serve numerous users. The lack of available workarounds means organizations must immediately upgrade to the patched versions to remediate this exposure, as manual mitigation approaches are not feasible.
Organizations should prioritize immediate deployment of the patched Nextcloud versions to address this vulnerability, as the risk persists until systems are updated. The patched releases include specific fixes that enhance temporary file handling procedures and implement proper access controls to prevent cross-user file access. Security teams should conduct comprehensive assessments of their Nextcloud deployments to identify affected versions and ensure all instances are updated. The vulnerability demonstrates the critical importance of proper file system isolation in multi-tenant applications and highlights the need for robust privilege separation mechanisms in cloud storage systems. Compliance with industry standards such as NIST SP 800-53 and ISO 27001 requires maintaining secure file handling practices, and this vulnerability represents a failure to meet those security requirements in the Nextcloud implementation.