CVE-2026-103287 in Ghost
Summary
by MITRE • 10/01/2026
Ghost versions 1.18.0 before 6.27.0 contain a server-side request forgery vulnerability in the webhooks feature that allows staff users to probe internal hosts. Attackers with staff privileges can craft webhook requests to access internal network resources from the Ghost server.
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Analysis
by VulDB Data Team • 10/01/2026
The identified security flaw resides within the Ghost content management platform, specifically affecting versions ranging from 1.18.0 up to but not including version 6.27.0. This vulnerability is classified as a Server-Side Request Forgery, commonly abbreviated as SSRF, which represents a critical class of web application vulnerabilities where an attacker manipulates the server into making HTTP requests to arbitrary destinations under its control or within its network environment. In this specific instance, the flaw is embedded in the webhook functionality, a feature designed to allow external services to trigger actions on Ghost when certain events occur, such as publishing new content. The core technical deficiency lies in the insufficient validation of user-supplied input used to define the target URL for these webhooks. While SSRF vulnerabilities are often associated with unauthenticated attackers exploiting public-facing endpoints, this particular implementation flaw permits exploitation by authenticated staff users who possess elevated privileges within the application hierarchy.
The operational impact of this vulnerability is significant because it effectively bypasses standard network perimeter defenses that typically protect internal infrastructure from external threats but may not restrict outbound requests initiated by trusted applications like Ghost itself. An attacker with staff-level access can craft malicious webhook configurations pointing to internal IP addresses, localhost endpoints, or cloud metadata services such as those found in Amazon EC2 instances at 169.254.169.254. By doing so, the attacker leverages the server's own network identity and permissions to probe internal hosts that would otherwise be inaccessible from outside the local network. This capability allows for detailed reconnaissance of the internal network topology, identification of running services on private interfaces, and potentially accessing sensitive data stored in internal databases or administrative panels that are not exposed to the public internet. The ability to access cloud metadata endpoints is particularly dangerous as it can lead to credential theft if those instances have IAM roles attached with excessive permissions.
From a classification perspective, this vulnerability aligns closely with CWE-918, which defines Server-Side Request Forgery (SSRF) flaws where the web server makes requests based on user input without proper validation of the destination address. It also relates to CWE-643, Improper Mitigation for Exfiltration Vulnerability in Data Validation Layers, as the lack of URL scheme and host verification allows data exfiltration or internal probing through legitimate application channels. In terms of offensive security frameworks, this behavior maps directly to MITRE ATT&CK technique T1598, specifically Subtechnique T1598.002 for Phishing for Information within Cloud Environments if cloud metadata is targeted, and more broadly to reconnaissance activities that facilitate lateral movement or privilege escalation by gathering intelligence about the internal network architecture. The vulnerability underscores the risk of over-privileged application accounts being used as a pivot point into deeper infrastructure layers.
Mitigation strategies must address both immediate remediation and long-term architectural improvements. The primary and most effective solution is to upgrade the Ghost installation to version 6.27.0 or later, where this specific SSRF flaw in the webhook handler has been patched with stricter input validation logic that rejects requests targeting private IP ranges, loopback addresses, and cloud metadata endpoints. For environments where immediate upgrading is not feasible due to compatibility constraints, network-level controls should be implemented as a compensating measure. This includes configuring firewall rules or reverse proxy settings on the Ghost server to restrict outbound HTTP traffic to only known external domains required for legitimate webhook operations, thereby blocking requests directed at internal IP ranges regardless of application-layer validation failures. Additionally, implementing strict least-privilege principles for staff accounts can limit the blast radius if such an account is compromised, ensuring that even with SSRF capabilities, the attacker cannot access highly sensitive administrative functions or critical data stores directly through the web interface. Regular auditing of webhook configurations and monitoring outbound network traffic from application servers are also recommended to detect any anomalous request patterns indicative of exploitation attempts.