CVE-2023-49103: ownCloud GraphAPI Information Disclosure

CVE-2023-49103 Overview

CVE-2023-49103 is a critical information disclosure vulnerability affecting ownCloud's GraphAPI application. The vulnerability exists in the owncloud/graphapi versions 0.2.x before 0.2.1 and 0.3.x before 0.3.1. The GraphAPI app relies on a third-party GetPhpInfo.php library that exposes a URL endpoint which, when accessed, reveals the complete PHP environment configuration via phpinfo() output.

This information disclosure is particularly severe in containerized deployments where environment variables may contain sensitive data such as ownCloud admin passwords, mail server credentials, and license keys. The vulnerability has been actively exploited in the wild and is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog.

Critical Impact

Unauthenticated attackers can remotely access sensitive configuration details including admin credentials, mail server passwords, and license keys in containerized ownCloud deployments. This vulnerability is actively exploited and listed in CISA KEV.

Affected Products

• ownCloud GraphAPI 0.2.0 (fixed in 0.2.1)
• ownCloud GraphAPI 0.3.0 (fixed in 0.3.1)
• Docker containers deployed after February 2023

Discovery Timeline

• 2023-11-21 - CVE-2023-49103 published to NVD
• 2025-10-31 - Last updated in NVD database

Technical Details for CVE-2023-49103

Vulnerability Analysis

The vulnerability stems from the ownCloud GraphAPI application's dependency on a third-party library that includes GetPhpInfo.php. This library provides a URL endpoint that, when accessed by any user (including unauthenticated attackers), executes the PHP phpinfo() function and returns its complete output over HTTP.

The phpinfo() function displays comprehensive information about the PHP environment, including all configured environment variables. In containerized deployments, particularly Docker-based installations, sensitive credentials are commonly passed as environment variables for configuration purposes. This design pattern, while convenient for deployment, becomes a severe security liability when combined with this vulnerability.

The exposure extends beyond just credential disclosure. The phpinfo() output reveals internal server paths, installed PHP extensions, loaded modules, compilation options, and other system details that provide valuable reconnaissance information for further attacks.

Root Cause

The root cause is the inclusion of a third-party debugging library (GetPhpInfo.php) that was intended for development purposes but remained accessible in production deployments. This library exposes the PHP phpinfo() function through an unauthenticated URL endpoint, creating an information disclosure path. Importantly, simply disabling the GraphAPI app does not eliminate the vulnerability, as the underlying library files remain accessible.

Attack Vector

The attack vector is network-based and requires no authentication or user interaction. An attacker can directly access the vulnerable URL endpoint to retrieve sensitive configuration data. The attack is trivial to execute, requiring only knowledge of the vulnerable endpoint URL.

The exploitation flow is straightforward:

1. Attacker identifies an ownCloud instance with the vulnerable GraphAPI version
2. Attacker accesses the GetPhpInfo.php endpoint directly via HTTP request
3. The server responds with complete phpinfo() output containing environment variables
4. Attacker extracts credentials such as OWNCLOUD_ADMIN_PASSWORD, OWNCLOUD_MAIL_SMTP_PASSWORD, and other sensitive values from the response

In containerized environments, attackers can immediately leverage extracted admin credentials to gain full control of the ownCloud instance. See the ownCloud Security Advisory for complete technical details.

Detection Methods for CVE-2023-49103

Indicators of Compromise

• HTTP requests to endpoints containing GetPhpInfo.php or similar phpinfo-exposing paths
• Unexpected external access to ownCloud GraphAPI endpoints from unknown IP addresses
• Log entries showing successful retrieval of PHP configuration pages
• Authentication attempts using credentials that were stored only in environment variables

Detection Strategies

• Monitor web server access logs for requests to GetPhpInfo.php or GraphAPI debugging endpoints
• Implement web application firewall (WAF) rules to block requests containing phpinfo patterns
• Review authentication logs for login attempts from unusual geographic locations after potential exposure
• Deploy network monitoring to detect data exfiltration patterns following reconnaissance activity

Monitoring Recommendations

• Enable verbose logging on ownCloud instances and forward to SIEM for analysis
• Configure alerts for any HTTP 200 responses to GraphAPI debugging endpoints
• Monitor for credential reuse attacks if exposure is suspected
• Implement file integrity monitoring on GraphAPI application directories

How to Mitigate CVE-2023-49103

Immediate Actions Required

• Upgrade ownCloud GraphAPI to version 0.2.1 or 0.3.1 or later immediately
• Delete the owncloud/apps/graphapi/vendor/microsoft/microsoft-graph/tests/GetPhpInfo.php file if upgrade is not immediately possible
• Rotate all credentials that may have been exposed via environment variables, including admin passwords and mail server credentials
• Review access logs to determine if the vulnerability was exploited before remediation

Patch Information

ownCloud has released patched versions that address this vulnerability. Users should upgrade to GraphAPI version 0.2.1 or 0.3.1 depending on their current version branch. The patches remove the vulnerable GetPhpInfo.php file and prevent future exposure of phpinfo() output through the application.

For detailed patch information and upgrade instructions, refer to the ownCloud Security Advisory.

Workarounds

• Manually delete the GetPhpInfo.php file from the GraphAPI vendor directory as an interim measure
• Implement network-level access controls to restrict access to ownCloud instances from trusted networks only
• Use a reverse proxy or WAF to block requests to the vulnerable endpoint pattern
• Consider migrating sensitive credentials from environment variables to more secure secret management solutions

# Remove vulnerable file as temporary workaround
rm -f /path/to/owncloud/apps/graphapi/vendor/microsoft/microsoft-graph/tests/GetPhpInfo.php

# Verify file has been removed
ls -la /path/to/owncloud/apps/graphapi/vendor/microsoft/microsoft-graph/tests/

# Block access via Apache .htaccess (if applicable)
echo '<Files "GetPhpInfo.php">' >> /path/to/owncloud/.htaccess
echo '    Require all denied' >> /path/to/owncloud/.htaccess
echo '</Files>' >> /path/to/owncloud/.htaccess