CVE-2026-6573: PHPEMS 11.0 SSRF Vulnerability

CVE-2026-6573 Overview

A Server-Side Request Forgery (SSRF) vulnerability has been identified in PHPEMS version 11.0, an open-source PHP-based examination management system. This vulnerability exists within the temppage function located in the file /app/exam/controller/exams.master.php, which is part of the Instant Exam Creation Handler component. By manipulating the uploadfile argument, an authenticated attacker can force the server to make arbitrary requests to internal or external resources.

Critical Impact

Authenticated attackers can exploit this SSRF vulnerability to access internal services, scan internal networks, or potentially exfiltrate sensitive data from systems that should not be accessible from external networks.

Affected Products

• PHPEMS 11.0

Discovery Timeline

• 2026-04-19 - CVE-2026-6573 published to NVD
• 2026-04-22 - Last updated in NVD database

Technical Details for CVE-2026-6573

Vulnerability Analysis

This vulnerability is classified as CWE-918 (Server-Side Request Forgery). The flaw exists in the Instant Exam Creation Handler functionality, specifically within the temppage function that processes file uploads. The uploadfile parameter is not properly validated or sanitized before being used to construct server-side requests.

When processing exam creation requests, the application accepts user-supplied URLs through the uploadfile parameter and makes server-side requests to fetch these resources. The lack of proper input validation allows attackers to redirect these requests to arbitrary destinations, including internal network resources that would otherwise be inaccessible.

The network-based attack vector requires low-privilege authenticated access but no user interaction, making it straightforward for any authenticated user to exploit. While the exploit is publicly known according to vulnerability databases, no active exploitation has been confirmed at this time.

Root Cause

The root cause of this vulnerability is insufficient validation of user-supplied input in the uploadfile parameter within the temppage function. The application fails to implement proper URL validation and allowlisting mechanisms, allowing attackers to specify arbitrary URLs including internal network addresses, localhost references, and cloud metadata endpoints.

Attack Vector

The attack is executed remotely over the network by an authenticated user. The attacker crafts a malicious request to the Instant Exam Creation Handler endpoint, providing a specially crafted URL in the uploadfile parameter. The server then processes this request and makes an outbound connection to the attacker-specified destination.

Common exploitation scenarios include:

• Accessing internal services on localhost (127.0.0.1) or internal network ranges
• Scanning internal network ports and services
• Accessing cloud provider metadata endpoints (e.g., 169.254.169.254)
• Retrieving sensitive configuration files or credentials from internal systems

The vulnerability can be exploited by sending crafted HTTP requests to /app/exam/controller/exams.master.php with a manipulated uploadfile parameter pointing to internal resources. For detailed technical analysis and proof-of-concept information, refer to the VulDB vulnerability entry and the VulnPlus Note Share documentation.

Detection Methods for CVE-2026-6573

Indicators of Compromise

• Unusual outbound connections from the PHPEMS web server to internal network addresses or cloud metadata endpoints
• Requests to /app/exam/controller/exams.master.php containing suspicious URLs in the uploadfile parameter (e.g., localhost, 127.0.0.1, 169.254.169.254, internal IP ranges)
• Server logs showing connections to unexpected internal services during exam creation operations
• Outbound traffic from the web application tier to services it should not normally communicate with

Detection Strategies

• Monitor web application logs for requests to the exams.master.php endpoint containing internal IP addresses or localhost references in URL parameters
• Implement network-level monitoring for outbound connections from web servers to internal network ranges that are not expected
• Deploy web application firewalls (WAF) with SSRF detection rules to block requests containing suspicious URL patterns in the uploadfile parameter
• Use SentinelOne's behavioral analysis capabilities to detect anomalous network activity originating from web application processes

Monitoring Recommendations

• Configure alerts for outbound connections from the PHPEMS server to RFC1918 private address ranges (10.x.x.x, 172.16-31.x.x, 192.168.x.x)
• Monitor for access attempts to cloud metadata endpoints (169.254.169.254) from application servers
• Review access logs for the Instant Exam Creation Handler endpoint for unusual request patterns

How to Mitigate CVE-2026-6573

Immediate Actions Required

• Restrict access to the Instant Exam Creation Handler functionality to trusted administrators only until a patch is available
• Implement network-level segmentation to limit what internal resources the PHPEMS server can access
• Deploy WAF rules to block SSRF attack patterns targeting the vulnerable endpoint
• If the uploadfile functionality is not required, consider disabling or removing it temporarily

Patch Information

No official vendor patch information is currently available for this vulnerability. Organizations should monitor the official PHPEMS project channels for security updates. In the interim, implement the workarounds and mitigations described below to reduce exposure.

For additional vulnerability details and updates, refer to the VulDB vulnerability database entry.

Workarounds

• Implement URL allowlisting at the application or reverse proxy level to restrict the uploadfile parameter to only trusted external domains
• Configure firewall rules to prevent the web server from initiating outbound connections to internal network ranges
• Use network segmentation to isolate the PHPEMS application from sensitive internal services
• Consider deploying a proxy for all outbound requests from the application that enforces URL validation and blocks requests to internal resources

# Example: Block outbound connections to internal networks from web server (iptables)
# Adjust interface and IP ranges according to your environment
iptables -A OUTPUT -o eth0 -d 10.0.0.0/8 -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -o eth0 -d 172.16.0.0/12 -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -o eth0 -d 192.168.0.0/16 -m owner --uid-owner www-data -j DROP
iptables -A OUTPUT -o eth0 -d 169.254.169.254 -m owner --uid-owner www-data -j DROP