CVE-2026-105643 in Ghost
Summary
by MITRE • 10/05/2026
Ghost is a Node.js content management system. From version 6.34.0 until 6.67.0, embed cards in the Ghost editor could bypass protections against stored cross-site scripting. Any staff user, including Contributors, could store scripts in post content that ran when another staff user opened the post in the editor, potentially compromising that user’s admin session. Self-hosted sites should leave the new security.embedPreviewUrl configuration option at its default value. This issue is fixed in version 6.67.0.
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Analysis
by VulDB Data Team • 10/05/2026
The vulnerability identified as a stored cross-site scripting flaw within Ghost, specifically affecting versions from 6.34.0 through 6.67.0, represents a significant security regression in the content management system's editor functionality. This issue stems from insufficient input validation and sanitization mechanisms applied to embed cards during the post creation or editing process. Embed cards are interactive elements that allow users to preview external media or links within their posts. In this flawed implementation, the application failed to properly neutralize malicious script payloads embedded within these card configurations before storing them in the database. Consequently, when a staff member with any level of access, including those restricted to Contributor roles which typically have limited permissions, crafted and saved a post containing such an embed card, the malicious JavaScript code was persisted on the server side rather than being executed immediately or rejected by input filters.
The operational impact of this vulnerability is severe due to its stored nature combined with the specific trigger condition involving the editor interface. Unlike reflected cross-site scripting where the victim must click a crafted link, here the payload lies dormant in the database until an authorized user opens the post for editing within the Ghost admin dashboard. When another staff member accesses the compromised post in the editor, the browser executes the embedded script in the context of the authenticated session. This execution environment grants the attacker's code access to sensitive cookies, local storage data, and administrative API endpoints associated with that specific user account. The primary consequence is the potential compromise of the victim’s admin session, allowing an attacker to escalate privileges from a low-level contributor role to full administrator control over the Ghost instance.
From a classification perspective, this vulnerability aligns closely with CWE-79, which describes Improper Neutralization of Input During Web Page Generation commonly known as Cross-site Scripting. More specifically, it falls under CWE-836, Use of Password-based Cryptography for Authorization, because the exploitation relies on hijacking valid authentication sessions to perform unauthorized actions. In terms of adversary tactics, this behavior maps directly to MITRE ATT&CK technique T1059, Command and Scripting Interpreter, as well as T1213, Data from Information Repositories, since the attacker stores malicious code in a repository (the post content) for later execution by privileged users. The attack vector is classified as Local Access with User Interaction because it requires an internal user to create content and another internal user to view that content within the administrative interface.
To mitigate this risk effectively, organizations running self-hosted instances of Ghost must ensure they are operating on version 6.67.0 or later where the code defects have been patched by developers who implemented stricter sanitization rules for embed card inputs. For environments unable to upgrade immediately due to compatibility constraints, administrators should verify that the security.embedPreviewUrl configuration option remains at its default value. This setting controls how preview URLs are handled and can help limit the attack surface associated with external resource loading within the editor. Additionally, implementing a Content Security Policy header in the web server configuration can provide an additional layer of defense by restricting script execution sources, although this is not a substitute for patching the underlying application vulnerability. Regular security audits and penetration testing focused on role-based access controls are recommended to detect similar logic flaws that might allow privilege escalation through other vectors within the CMS ecosystem.