CVE-2026-3530 Overview
A Server-Side Request Forgery (SSRF) vulnerability has been identified in the Drupal OpenID Connect / OAuth client module. This security flaw allows attackers to manipulate server-side requests, potentially enabling unauthorized access to internal resources, data exfiltration, and exploitation of internal services that would otherwise be inaccessible from external networks.
Critical Impact
This SSRF vulnerability could allow attackers to bypass network security controls, access internal services, scan internal networks, and potentially pivot to other systems within the organization's infrastructure.
Affected Products
- Drupal OpenID Connect / OAuth client versions from 0.0.0 before 1.5.0
Discovery Timeline
- March 26, 2026 - CVE-2026-3530 published to NVD
- March 26, 2026 - Last updated in NVD database
Technical Details for CVE-2026-3530
Vulnerability Analysis
This vulnerability falls under CWE-918 (Server-Side Request Forgery), which occurs when a web application fetches remote resources based on user-supplied input without proper validation. In the context of the Drupal OpenID Connect / OAuth client module, the SSRF vulnerability allows attackers to craft malicious requests that the server will execute on their behalf.
The OpenID Connect / OAuth client module is designed to facilitate authentication through external identity providers. During the OAuth flow, the module must communicate with external authorization servers to validate tokens and retrieve user information. The vulnerability exists in how the module handles URLs or endpoint configurations, allowing an attacker to redirect these server-side requests to arbitrary destinations.
Root Cause
The root cause of this vulnerability lies in insufficient validation of user-controlled input that influences server-side HTTP requests. The OpenID Connect / OAuth client module fails to properly sanitize or restrict URLs before making outbound requests, allowing attackers to specify arbitrary internal or external endpoints. This lack of input validation enables the server to be weaponized as a proxy for malicious requests.
Attack Vector
An attacker can exploit this SSRF vulnerability by manipulating OAuth-related parameters or configuration endpoints to point to internal resources or malicious external servers. The attack vector typically involves:
- Identifying input fields or parameters that influence server-side URL requests
- Crafting malicious payloads containing internal IP addresses, localhost references, or cloud metadata endpoints
- Submitting the crafted input to trigger the vulnerable server to make requests on the attacker's behalf
- Leveraging the server's network position to access resources not directly reachable from external networks
Common SSRF attack targets include internal services (such as databases, admin panels, and monitoring systems), cloud metadata services (like AWS IMDSv1 at 169.254.169.254), and internal network scanning to map infrastructure.
Detection Methods for CVE-2026-3530
Indicators of Compromise
- Unusual outbound HTTP/HTTPS requests from the Drupal server to internal IP ranges (e.g., 10.x.x.x, 172.16.x.x, 192.168.x.x)
- Requests to cloud metadata endpoints such as 169.254.169.254
- Unexpected traffic patterns from the web server to internal services not typically accessed
- Log entries showing OAuth-related requests with suspicious or internal URLs
Detection Strategies
- Implement network monitoring to detect anomalous outbound connections from web servers to internal resources
- Configure web application firewalls (WAF) to detect and block SSRF patterns in request parameters
- Review Drupal access logs for suspicious OAuth callback URLs or authorization endpoints
- Deploy intrusion detection systems (IDS) with signatures for common SSRF payloads
Monitoring Recommendations
- Enable detailed logging for all outbound HTTP requests made by the Drupal application
- Monitor DNS queries from the web server for internal hostname resolution attempts
- Set up alerts for connections to cloud metadata services or internal infrastructure from DMZ servers
- Implement egress filtering and monitor for policy violations
How to Mitigate CVE-2026-3530
Immediate Actions Required
- Upgrade the Drupal OpenID Connect / OAuth client module to version 1.5.0 or later immediately
- Review and restrict outbound network access from Drupal servers using firewall rules
- Implement allowlisting for permitted OAuth provider endpoints
- Audit existing OAuth configurations for any signs of tampering or malicious modifications
Patch Information
The vulnerability has been addressed in version 1.5.0 of the OpenID Connect / OAuth client module. Organizations should update to this version or later to remediate the vulnerability. For detailed patch information and security advisory, refer to the Drupal Security Advisory.
Workarounds
- Implement strict URL allowlisting at the application level, permitting only known OAuth provider domains
- Deploy network-level egress filtering to prevent the Drupal server from connecting to internal IP ranges
- Use a web application firewall (WAF) with SSRF protection rules to filter malicious requests
- Disable or restrict the OpenID Connect / OAuth client module until patching is possible if not critical to operations
# Example: Network egress filtering with iptables to block internal IP access
# Block requests to internal RFC1918 ranges from the web server
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 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.
