CVE-2026-3163 Overview
A Server-Side Request Forgery (SSRF) vulnerability has been identified in SourceCodester Website Link Extractor version 1.0. This vulnerability affects the file_get_contents function within the URL Handler component, allowing attackers to manipulate the application into making unauthorized requests to internal or external resources. The attack can be initiated remotely, and exploit details have been publicly disclosed.
Critical Impact
Attackers can leverage this SSRF vulnerability to access internal services, bypass firewalls, perform port scanning of internal networks, and potentially exfiltrate sensitive data from systems that should not be accessible from the internet.
Affected Products
- SourceCodester Website Link Extractor 1.0
- remyandrade website_link_extractor 1.0
Discovery Timeline
- February 25, 2026 - CVE-2026-3163 published to NVD
- February 25, 2026 - Last updated in NVD database
Technical Details for CVE-2026-3163
Vulnerability Analysis
The vulnerability resides in the URL Handler component of SourceCodester Website Link Extractor, specifically in how the application processes user-supplied URLs through the PHP file_get_contents function. This function is used to fetch content from remote URLs to extract links, but the implementation lacks proper input validation and URL sanitization.
When a user submits a URL for link extraction, the application passes this input directly to file_get_contents without verifying that the target URL points to an appropriate external resource. This allows attackers to specify internal network addresses, localhost references, or cloud metadata endpoints as targets.
The vulnerability enables attackers to probe internal network infrastructure, access internal services that are not exposed to the internet, and potentially retrieve sensitive configuration data from cloud environments. This weakness is classified under CWE-918 (Server-Side Request Forgery).
Root Cause
The root cause of this vulnerability is improper input validation in the URL Handler component. The application fails to implement several critical security controls:
- No URL scheme validation - The application does not restrict URL schemes, potentially allowing file://, gopher://, or other dangerous protocols
- Missing internal IP address filtering - Private IP ranges (10.x.x.x, 172.16.x.x-172.31.x.x, 192.168.x.x) and localhost (127.0.0.1) are not blocked
- Absent DNS rebinding protection - The application does not verify that resolved hostnames remain external after DNS resolution
- No allowlist enforcement - There is no restriction on which domains or IP addresses the application can connect to
Attack Vector
The attack vector is network-based and can be exploited remotely by any authenticated user. The attacker submits a malicious URL to the link extraction functionality, causing the server to make requests on behalf of the attacker.
Typical attack scenarios include:
- Internal network reconnaissance: Submitting URLs like http://192.168.1.1/ or http://10.0.0.1/admin to discover and interact with internal services
- Cloud metadata access: On cloud platforms, targeting metadata endpoints such as http://169.254.169.254/latest/meta-data/ to retrieve instance credentials
- Port scanning: Systematically probing internal hosts to identify running services
- Bypassing access controls: Accessing internal APIs or admin panels that trust requests from the server's IP address
The vulnerability is exploited by manipulating the URL input parameter to point to internal resources. Since the file_get_contents function fetches content from the specified URL on the server side, attackers can leverage the server's network position to access resources otherwise inaccessible from the internet. For detailed technical analysis, refer to the Medium Blog on SSRF Vulnerability.
Detection Methods for CVE-2026-3163
Indicators of Compromise
- HTTP requests from the web server to internal IP addresses (10.x.x.x, 172.16.x.x-172.31.x.x, 192.168.x.x, 127.0.0.1)
- Requests to cloud metadata endpoints (169.254.169.254) originating from the application server
- Unusual outbound connections to internal network ports (22, 3306, 5432, 6379, etc.)
- Server logs showing URL submissions containing localhost or private IP addresses
Detection Strategies
- Monitor application logs for URL parameters containing internal IP addresses, localhost references, or cloud metadata URLs
- Implement network-level monitoring to detect outbound connections from the web server to internal network segments
- Deploy web application firewall (WAF) rules to flag or block SSRF attack patterns in user input
- Review server access logs for unusual patterns of requests to internal services
Monitoring Recommendations
- Enable detailed logging on the URL Handler component to capture all submitted URLs
- Configure network intrusion detection systems (IDS) to alert on internal traffic originating from DMZ servers
- Set up alerts for any connections from the application server to sensitive internal systems or cloud metadata endpoints
- Implement real-time monitoring of outbound traffic patterns from the affected application
How to Mitigate CVE-2026-3163
Immediate Actions Required
- Disable the URL extraction functionality if not critical to business operations until a patch is available
- Implement network segmentation to restrict the web server's ability to reach internal systems
- Deploy WAF rules to block requests containing internal IP addresses or metadata endpoints
- Review access logs for evidence of exploitation attempts
Patch Information
No official vendor patch has been released at the time of publication. Organizations should monitor the SourceCodester Resource Hub for security updates. Given the public disclosure of this vulnerability, consider implementing compensating controls or removing the application from production environments until a patch becomes available.
For additional vulnerability details and tracking information, refer to VulDB #347670.
Workarounds
- Implement a URL allowlist that restricts the application to only fetch content from approved external domains
- Add server-side validation to block private IP ranges, localhost, and cloud metadata addresses in URL parameters
- Deploy network-level controls (firewall rules) to prevent the web server from initiating connections to internal networks
- Consider using a proxy server with strict egress filtering for all outbound HTTP requests from the application
# Example iptables rules to restrict outbound connections from the web server
# Block connections to private IP ranges
iptables -A OUTPUT -d 10.0.0.0/8 -j DROP
iptables -A OUTPUT -d 172.16.0.0/12 -j DROP
iptables -A OUTPUT -d 192.168.0.0/16 -j DROP
iptables -A OUTPUT -d 127.0.0.0/8 -j DROP
# Block cloud metadata endpoint
iptables -A OUTPUT -d 169.254.169.254 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
