CVE-2026-31317: Craftql SSRF Vulnerability

CVE-2026-31317 Overview

CVE-2026-31317 is a Server-Side Request Forgery (SSRF) vulnerability affecting CraftQL version 1.3.7 and earlier. This vulnerability exists within the vendor/markhuot/craftql/src/Listeners/GetAssetsFieldSchema.php file and allows an attacker to execute arbitrary code by exploiting improper input validation in the GraphQL API layer. CraftQL is a popular GraphQL plugin for the Craft CMS platform, making this vulnerability particularly concerning for organizations using this content management system.

Critical Impact

Attackers can leverage this SSRF vulnerability to make arbitrary server-side requests, potentially accessing internal services, cloud metadata endpoints, or executing arbitrary code on vulnerable CraftQL installations.

Affected Products

• CraftQL v1.3.7 and earlier versions
• Craft CMS installations using vulnerable CraftQL plugin versions
• GraphQL endpoints exposed through CraftQL

Discovery Timeline

• 2026-04-17 - CVE CVE-2026-31317 published to NVD
• 2026-04-20 - Last updated in NVD database

Technical Details for CVE-2026-31317

Vulnerability Analysis

This SSRF vulnerability resides in the GetAssetsFieldSchema.php listener component of CraftQL. The flaw stems from insufficient validation of user-supplied URLs or resource identifiers within the asset handling functionality of the GraphQL schema. When processing asset-related queries, the vulnerable code fails to properly sanitize or restrict outbound requests, enabling attackers to craft malicious GraphQL queries that force the server to make requests to arbitrary destinations.

The vulnerability is network-accessible without requiring authentication or user interaction, meaning attackers can exploit it remotely against any exposed CraftQL endpoint. The primary impact is confidentiality breach, as attackers can use the SSRF to exfiltrate sensitive data from internal network resources, cloud infrastructure metadata services (such as AWS IMDSv1 endpoints), or other services accessible from the vulnerable server.

Root Cause

The root cause of CVE-2026-31317 is improper input validation (CWE-918: Server-Side Request Forgery) within the GetAssetsFieldSchema.php file. The asset field schema listener accepts user-controlled input that is subsequently used to construct server-side HTTP requests without adequate validation of the destination URL. This allows attackers to specify arbitrary URLs, including internal IP addresses, localhost services, and cloud metadata endpoints that should not be accessible from external requests.

Attack Vector

The attack vector is network-based, exploiting the GraphQL API endpoint exposed by CraftQL. An attacker can craft a malicious GraphQL query targeting the assets field functionality, supplying a URL pointing to internal services or sensitive metadata endpoints. When the vulnerable server processes this query, it makes the attacker-specified request from its own network context, bypassing firewall restrictions and accessing resources that would otherwise be inaccessible from the external network.

The exploitation flow typically involves:

1. Identifying a CraftQL endpoint on the target Craft CMS installation
2. Crafting a GraphQL query that targets the vulnerable asset handling functionality
3. Specifying a malicious URL pointing to internal services or cloud metadata endpoints
4. Extracting the response data returned by the server-side request

Technical details and proof-of-concept information are available in the SSRF exploit repository and the detailed README documentation.

Detection Methods for CVE-2026-31317

Indicators of Compromise

• Unusual GraphQL queries targeting asset fields with external or internal IP addresses as parameters
• Server-side requests to cloud metadata endpoints (e.g., 169.254.169.254) originating from the web server
• Abnormal outbound network traffic from CraftQL application servers to internal services
• GraphQL query logs showing URL manipulation attempts in asset-related operations

Detection Strategies

• Implement GraphQL query logging and monitor for suspicious patterns in asset field queries
• Deploy network monitoring to detect server-side requests to internal IP ranges or cloud metadata services
• Configure Web Application Firewall (WAF) rules to detect SSRF patterns in GraphQL payloads
• Use SentinelOne Singularity to monitor for anomalous network behavior from web application processes

Monitoring Recommendations

• Enable detailed logging for all GraphQL API endpoints and audit asset-related queries
• Monitor outbound connections from web servers for requests to RFC 1918 private IP addresses
• Configure alerts for any access attempts to cloud provider metadata endpoints
• Review CraftQL logs for unusual URL patterns or encoding attempts in query parameters

How to Mitigate CVE-2026-31317

Immediate Actions Required

• Upgrade CraftQL to the latest version that addresses this vulnerability
• Restrict network egress from web servers to only necessary external destinations
• Implement URL allowlisting for any asset fetching functionality
• Disable or restrict access to GraphQL endpoints if not required for public access

Patch Information

Organizations should check the CraftQL GitHub repository for updated versions that address this SSRF vulnerability. Until a patch is applied, organizations should implement network-level controls to limit the impact of potential exploitation.

Workarounds

• Implement strict URL validation and allowlisting at the application or WAF level for asset requests
• Block outbound connections from web servers to internal IP ranges and cloud metadata endpoints using firewall rules
• Place CraftQL servers in a network segment with limited access to sensitive internal resources
• Consider temporarily disabling the vulnerable asset functionality if not critical to operations
• Use cloud provider IMDS v2 (token-based) if running on AWS to prevent metadata access via SSRF

# Example firewall rules to block common SSRF targets
# Block access to cloud metadata endpoints
iptables -A OUTPUT -d 169.254.169.254 -j DROP

# Block access to internal RFC 1918 ranges from 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

# Allow only necessary outbound connections
iptables -A OUTPUT -p tcp --dport 443 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 80 -j ACCEPT