CVE-2025-53828: Server-Side Request Forgery in SharePoint for ownCloud Enables Admin Code Execution

Technical summary

CVE-2025-53828 is a server-side request forgery (SSRF) vulnerability (CWE-918) in SharePoint for ownCloud versions prior to 0.4.1. The flaw resides in the SharePoint application module for ownCloud Classic and permits authenticated administrators to craft requests that, when processed by the application, allow execution of arbitrary code on the underlying system. The vulnerability requires administrative privileges to trigger but results in full system compromise once exploited, affecting confidentiality, integrity, and availability.

Business impact

The risk is primarily insider threat and account compromise. If an admin account is compromised through phishing, credential theft, or other means, an attacker gains a direct path to remote code execution on your ownCloud infrastructure. For organizations using ownCloud for sensitive file storage and collaboration, this means potential data exfiltration, ransomware deployment, or operational disruption. The impact is high because ownCloud often sits in trusted network positions and handles confidential business documents.

Affected systems

ownCloud 10 versions prior to 10.15.3 with the SharePoint for ownCloud application enabled are vulnerable. The SharePoint app is an optional integration module; affected organizations are those explicitly using it for SharePoint interoperability. Verify your ownCloud version and check whether the SharePoint app is installed and active in your deployment.

Exploitability

Exploitation requires valid administrative credentials, which sets the bar higher than an unauthenticated attack. However, admin accounts are high-value targets and are sometimes compromised in broader attacks or through insider malice. Once an attacker has admin access, the SSRF flaw is straightforward to chain into code execution—no special tools or multi-step exploitation is needed. The ease of exploitation given admin access is reflected in the moderate attack complexity (AC:H in CVSS context).

Remediation

Upgrade ownCloud 10 to version 10.15.3 or later. This update includes SharePoint for ownCloud 0.4.1, the patched version that removes the SSRF vulnerability. If you cannot upgrade immediately, restrict administrative access to trusted individuals only, enforce strong password policies, and consider temporarily disabling the SharePoint app if it is not actively required.

Patch guidance

Apply the ownCloud 10.15.3 or later update as soon as feasible. Verify the patch through your vendor's official release notes or advisory. Test in a non-production environment first to ensure compatibility with your deployment. If you are on a different major version (e.g., ownCloud 11 or later), confirm that the corresponding SharePoint app version includes the fix before deploying.

Detection guidance

Monitor for suspicious requests originating from the SharePoint for ownCloud application, particularly those that attempt to contact internal IP addresses or non-standard ports from the ownCloud server. Review audit logs for administrative actions involving the SharePoint app module, especially requests to create or modify SharePoint connections. Network-level monitoring for outbound connections from your ownCloud instance to unusual destinations may surface exploitation attempts. Endpoint detection and response (EDR) tools should flag unexpected child processes spawned by ownCloud services.

Why prioritize this

Although this vulnerability requires admin credentials to exploit, the consequence of successful compromise is severe—arbitrary code execution with system privileges. For security teams, the key is assessing the likelihood of admin account compromise in your threat model. If you operate in a high-security environment with robust identity controls, the risk is lower. In less mature environments or those facing advanced adversaries, this should be prioritized. The CVSS score of 8.5 (HIGH) reflects the high impact but moderate exploitability balance.

Risk score, explained

The CVSS 3.1 score of 8.5 is driven by the attack vector being network-accessible (AV:N) and the impact being severe across all three categories (confidentiality, integrity, and availability). The requirement for prior authentication (PR:L) and the higher attack complexity (AC:H) prevent this from being a critical score, but the cross-boundary impact (S:C) and the ability to execute arbitrary code place it firmly in the HIGH severity tier. This reflects a real but not trivial threat that warrants timely patching.

Frequently asked questions