CVE-2025-53831 Overview
CVE-2025-53831 is a stored Cross-Site Scripting (XSS) vulnerability affecting DrawIO for ownCloud, an integration application that enables DrawIO diagramming inside ownCloud Classic. The flaw stems from improper neutralization of input during web page generation [CWE-79]. Attackers with access to the DrawIO app can inject persistent scripts that execute in the browser context of other users viewing affected diagrams. The vulnerability affects DrawIO for ownCloud versions prior to 1.0.2 and ownCloud 10 versions prior to 10.15.3. Successful exploitation can lead to session compromise, data theft, and unauthorized actions performed on behalf of victims within the ownCloud instance.
Critical Impact
Authenticated attackers can store malicious scripts in DrawIO diagrams that execute against any user opening the shared content, enabling account takeover within ownCloud.
Affected Products
- DrawIO for ownCloud versions prior to 1.0.2
- ownCloud 10 versions prior to 10.15.3
- ownCloud Classic deployments using the DrawIO integration
Discovery Timeline
- 2026-07-06 - CVE-2025-53831 published to NVD
- 2026-07-06 - Last updated in NVD database
Technical Details for CVE-2025-53831
Vulnerability Analysis
The vulnerability resides in the DrawIO for ownCloud application, which integrates the DrawIO diagram editor with ownCloud Classic file storage. The application fails to properly neutralize user-supplied input before rendering it in generated web pages. This omission allows an attacker with access to the DrawIO app to inject arbitrary HTML or JavaScript content into diagram data. When another authenticated user opens the compromised diagram, the browser parses and executes the injected payload in the context of the ownCloud origin.
Because the payload is persisted server-side, the attack qualifies as stored XSS, which is more severe than reflected variants. The attack scope changes across a security boundary since script executing in one user's browser can act on their session tokens and privileges. Successful exploitation supports session hijacking, exfiltration of file contents accessible to the victim, forced sharing changes, and pivoting to administrative accounts if an admin views the payload.
Root Cause
The root cause is [CWE-79] Improper Neutralization of Input During Web Page Generation. The DrawIO integration accepts diagram content or associated metadata containing markup and reflects it into HTML output without sufficient encoding or sanitization. Any characters that carry semantic meaning in HTML, such as <, >, and ", are not escaped before being placed into the rendered document.
Attack Vector
An attacker requires authenticated access to the DrawIO app within ownCloud. The attacker crafts a diagram containing a JavaScript payload embedded in a field that is not properly sanitized. The attacker then shares the diagram with a target user or places it in a shared folder. When the victim opens the diagram, the payload executes in the victim's browser under the ownCloud domain. User interaction is required for exploitation, since the victim must open or view the affected resource. See the GitHub Security Advisory GHSA-r9j8-fr2h-m47q for additional technical details.
Detection Methods for CVE-2025-53831
Indicators of Compromise
- Diagram files stored in ownCloud containing HTML tags such as <script>, <img onerror=>, or <svg onload=> in text or metadata fields
- Unexpected outbound HTTP requests from user browsers to attacker-controlled domains after opening DrawIO diagrams
- Anomalous session activity or API calls originating from user accounts shortly after viewing shared diagrams
Detection Strategies
- Review DrawIO diagram content stored on the ownCloud server for embedded script tags, event handler attributes, and encoded JavaScript payloads.
- Inspect ownCloud audit logs for suspicious sharing patterns targeting privileged users with DrawIO files from lower-privileged accounts.
- Monitor browser Content Security Policy (CSP) violation reports to identify script execution attempts blocked by policy.
Monitoring Recommendations
- Enable and centralize ownCloud application logs and web server access logs for correlation.
- Alert on file uploads or edits to DrawIO diagrams that contain HTML control characters in unexpected fields.
- Track authentication events and session token usage for anomalies following diagram access events.
How to Mitigate CVE-2025-53831
Immediate Actions Required
- Upgrade ownCloud 10 to version 10.15.3 or later, or upgrade DrawIO for ownCloud to version 1.0.2 or later.
- Audit existing DrawIO diagrams for embedded scripts and remove or sanitize any suspicious content prior to patching.
- Restrict access to the DrawIO app to trusted users until patching is complete.
Patch Information
The vendor has released fixes in DrawIO for ownCloud version 1.0.2 and ownCloud Classic version 10.15.3. Administrators should apply these updates through the standard ownCloud update process. Refer to the ownCloud Security Advisory GHSA-r9j8-fr2h-m47q for release details.
Workarounds
- Disable the DrawIO for ownCloud application until the patched version can be deployed.
- Enforce a strict Content Security Policy that disallows inline scripts on ownCloud domains to reduce XSS execution impact.
- Limit DrawIO app permissions so that only vetted users can create or share diagrams during the remediation window.
# Configuration example: disable the DrawIO app via occ until patched
sudo -u www-data php occ app:disable drawio
# After upgrading ownCloud to 10.15.3 or DrawIO to 1.0.2, re-enable
sudo -u www-data php occ app:enable drawio
sudo -u www-data php occ upgrade
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
