Ghost CMS Server-Side Request Forgery in Image Dimension Refetching

Executive Summary

This is a Server-Side Request Forgery (SSRF) vulnerability in Ghost versions from 3.20.2 before 6.51.0. Authenticated staff users can manipulate image cards to trigger outbound HTTP requests to arbitrary URLs, including internal network endpoints or attacker-controlled hosts. This allows access to metadata services and internal resources normally inaccessible from the public internet.

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Detection Guidance

To detect this SSRF vulnerability in Ghost, check for outbound HTTP requests from your Ghost server to unusual or internal IP addresses. Monitor logs for image card fetches to unexpected domains. Use network traffic analysis tools like tcpdump or Wireshark to inspect HTTP requests originating from the Ghost application.

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Impact Analysis

An attacker with staff access could exploit this to access internal network resources, steal sensitive data, or interact with internal services. This could lead to data breaches, unauthorized access to systems, or further network compromise depending on the internal setup.

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Compliance Impact

This vulnerability could lead to unauthorized data access or exfiltration, violating GDPR's data protection principles or HIPAA's security requirements for protected health information. Organizations may face compliance violations, legal penalties, or reputational damage if exploited.

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Mitigation Strategies

Upgrade Ghost to version 6.51.0 or later immediately to patch the vulnerability. If upgrading is not possible, restrict network access for the Ghost server to prevent outbound requests to internal or sensitive endpoints. Review and audit image card configurations for suspicious URLs.

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