CVE-2025-53828: ownCloud SharePoint App RCE Vulnerability

CVE-2025-53828 Overview

CVE-2025-53828 is a Server-Side Request Forgery (SSRF) vulnerability in the SharePoint for ownCloud application. The flaw affects SharePoint for ownCloud versions prior to 0.4.1, corresponding to ownCloud Classic releases prior to 10.15.3. An attacker holding administrative privileges can abuse the SSRF condition in the SharePoint app to execute arbitrary code on the underlying system. The vulnerability is tracked under CWE-918: Server-Side Request Forgery and is fixed in SharePoint for ownCloud 0.4.1, shipped with ownCloud 10.15.3.

Critical Impact
Authenticated administrators can pivot from an SSRF condition to arbitrary code execution on the ownCloud host, compromising confidentiality, integrity, and availability of stored files and adjacent services.

Affected Products

SharePoint for ownCloud versions prior to 0.4.1
ownCloud Classic 10 versions prior to 10.15.3
Deployments integrating ownCloud with Microsoft SharePoint through the affected app

Discovery Timeline

2026-07-06 - CVE-2025-53828 published to NVD
2026-07-08 - Last updated in NVD database

Technical Details for CVE-2025-53828

Vulnerability Analysis

The SharePoint for ownCloud app allows ownCloud Classic to integrate with Microsoft SharePoint document stores for synchronization and sharing. The application accepts server-side URL inputs when configuring or interacting with SharePoint endpoints. Prior to version 0.4.1, the app does not adequately validate or restrict these URLs. An administrator can point the SharePoint integration at attacker-controlled or otherwise unintended destinations. The resulting SSRF primitive is powerful enough to be chained into arbitrary code execution on the ownCloud server, as noted in the ownCloud security advisory GHSA-4m66-rpfj-m5f6.

Root Cause

The root cause is insufficient validation of outbound request targets within the SharePoint app request handler. User-controllable URL parameters flow into server-side HTTP request functions without allow-listing schemes, hostnames, or IP ranges. This exposes internal metadata services, loopback interfaces, and adjacent internal systems to attacker-controlled requests, and enables the code execution chain described by the vendor.

Attack Vector

Exploitation requires an authenticated administrative account on the ownCloud instance. The attacker configures or triggers the SharePoint app to issue server-side requests to a target of their choosing. Because administrator context is required, complexity is higher, but the impact spans full compromise of the ownCloud host. No user interaction is required, and the network attack vector allows exploitation from any location that can reach the ownCloud admin interface. The vulnerability does not have a public proof of concept at the time of publication, and it is not listed in the CISA Known Exploited Vulnerabilities catalog.

Detection Methods for CVE-2025-53828

Indicators of Compromise

Unexpected outbound HTTP or HTTPS requests originating from the ownCloud server process to internal IP ranges, loopback addresses, or cloud metadata endpoints such as 169.254.169.254.
Modifications to SharePoint app configuration entries in the ownCloud database made by administrator accounts outside normal change windows.
New or modified files under the ownCloud web root or app directories following SharePoint integration changes.

Detection Strategies

Inspect ownCloud application logs and web server access logs for administrative requests targeting SharePoint app endpoints followed by anomalous outbound connections.
Monitor process execution on the ownCloud host for child processes spawned by the PHP-FPM or web server user shortly after SharePoint app activity.
Verify the installed SharePoint for ownCloud version and flag any instance running below 0.4.1 or ownCloud Classic below 10.15.3.

Monitoring Recommendations

Alert on egress traffic from the ownCloud server to non-approved destinations, especially private RFC1918 ranges and metadata services.
Track administrator authentications and correlate them with subsequent app configuration changes.
Baseline expected SharePoint endpoints and alert on deviations in the configured URL fields.

How to Mitigate CVE-2025-53828

Immediate Actions Required

Upgrade ownCloud Classic to version 10.15.3 or later to receive SharePoint for ownCloud 0.4.1.
Audit all administrator accounts on ownCloud and rotate credentials for any account that may have been misused.
Review recent SharePoint app configuration changes and outbound request logs for signs of abuse.

Patch Information

The vendor fixed the SSRF and associated code execution path in SharePoint for ownCloud 0.4.1, which is bundled with ownCloud Classic 10.15.3. Details are documented in the ownCloud GitHub Security Advisory GHSA-4m66-rpfj-m5f6. Administrators should follow the standard ownCloud upgrade procedure and confirm the app version after the upgrade completes.

Workarounds

Disable the SharePoint for ownCloud app until the upgrade to 10.15.3 can be completed.
Restrict administrative access to ownCloud to trusted management networks and enforce multi-factor authentication for administrator accounts.
Apply egress filtering on the ownCloud host to block outbound requests to internal networks and cloud metadata endpoints.

bash

# Configuration example: disable the SharePoint app via occ until patched
sudo -u www-data php /var/www/owncloud/occ app:disable sharepoint

# Verify installed versions after upgrade
sudo -u www-data php /var/www/owncloud/occ status
sudo -u www-data php /var/www/owncloud/occ app:list | grep sharepoint