CVE-2026-103266 in Ghost
Summary
by MITRE • 10/01/2026
Ghost versions 5.2.0 through versions prior to 6.62.0 allow a remote attacker, without authentication, to abuse the Stripe Checkout flow to attach a paid subscription to an existing member, modify that member's name, and inject content into newsletters sent to the member. Depending on the recipient's email client, the injected content may be rendered, resulting in HTML injection or cross-site scripting (XSS).
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Analysis
by VulDB Data Team • 10/01/2026
The vulnerability identified within Ghost versions 5.2.0 through those prior to version 6.62.0 represents a critical security flaw rooted in insufficient access control and input validation mechanisms during the Stripe Checkout integration process. This issue allows an unauthenticated remote attacker to manipulate the subscription workflow, which is designed to handle billing and membership transitions securely. By exploiting this weakness, an adversary can bypass authentication requirements entirely, leveraging the application's trust in external payment service providers to execute unauthorized actions against existing user accounts. The core of the flaw lies in the failure to properly validate ownership or authorization when associating a paid subscription with a specific member profile, as well as inadequate sanitization of data fields that are subsequently rendered in email communications.
From an operational perspective, this vulnerability enables several malicious outcomes that compromise both confidentiality and integrity within the platform. An attacker can attach a paid subscription to any existing member account without their knowledge or consent, potentially leading to financial fraud if billing details are misappropriated or if the victim is charged for services they did not authorize. Furthermore, the ability to modify the member's name indicates a broader compromise of user data integrity, allowing attackers to impersonate legitimate users within the system context. This manipulation can be used to deceive other community members or administrators who rely on accurate identity information for trust and communication purposes.
The most severe aspect of this vulnerability involves the injection of arbitrary content into newsletters sent to the targeted member. Since Ghost utilizes these emails for regular communications, any malicious payload embedded in the name field or associated metadata will be transmitted directly to subscribers. Depending on the email client used by the recipient, such as Outlook, Gmail, or Apple Mail, the injected HTML may render fully rather than being displayed as plain text. This renders condition creates a direct pathway for cross-site scripting attacks against end-users who open these newsletters. Attackers can embed malicious JavaScript code that executes in the context of the victim's session with Ghost, potentially allowing for cookie theft, session hijacking, or redirection to phishing sites designed to harvest credentials.
This vulnerability aligns closely with CWE-284, which describes Improper Access Control, as it permits unauthorized actors to perform actions reserved for authenticated users or specific administrative functions. Additionally, the potential for HTML injection and cross-site scripting maps directly to CWE-79, known as Improper Neutralization of Input During Web Page Generation. In terms of offensive security frameworks, this exploit leverages techniques associated with ATT&CK ID T1059, specifically Command and Scripting Interpreter via web applications, by using the newsletter delivery mechanism as a vector for executing malicious scripts in the victim's browser environment. The lack of authentication required to trigger these actions also reflects weaknesses consistent with CWE-862, Missing Authorization checks within critical business logic flows.
To mitigate this risk, organizations running affected versions must upgrade immediately to Ghost version 6.62.0 or later, where these access control and input validation issues have been addressed by the development team. Until an upgrade is feasible, administrators should consider implementing strict Web Application Firewall rules that monitor for anomalous patterns in Stripe webhook requests and checkout session modifications. It is also advisable to enforce Content Security Policy headers on any web interfaces involved in user profile management to limit script execution capabilities, although this will not fully prevent the initial exploitation of the subscription attachment flaw. Regular auditing of membership records and newsletter content delivery logs can help detect unauthorized changes or suspicious injection attempts early in their lifecycle.