CVE-2026-103289 in Ghost
Summary
by MITRE • 10/01/2026
Ghost from 5.9.0 before 6.44.1 contains an input validation issue in the comments feature that allows authenticated members to access comments they are not authorized to view, resulting in disclosure of restricted comment data.
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Analysis
by VulDB Data Team • 10/01/2026
The vulnerability identified within Ghost versions prior to 6.44.1 represents a critical failure in server-side access control logic specifically affecting the platform's commenting subsystem. This flaw is classified as an Authorization Bypass issue where the application fails to properly enforce restrictions on which resources authenticated users are permitted to access. In a typical content management system like Ghost, comments associated with specific posts or pages often contain sensitive information, user interactions, and potentially private discussions that should be restricted based on the relationship between the comment author, the post owner, and the viewer's role. The vulnerability arises because the backend API endpoint responsible for retrieving comment data does not adequately validate whether the requesting authenticated member has explicit permission to view the specific comments being requested. This oversight allows an attacker who possesses valid credentials for any registered user account on the target instance to manipulate request parameters or exploit logic flaws in the retrieval process to fetch comments intended for other users, administrators, or private groups.
From a technical perspective, this issue aligns with CWE-284 Improper Access Control and CWE-601 URL Redirection to Untrusted Destination if the vulnerability involves redirecting requests to unauthorized endpoints, though it is primarily an authorization bypass. The attacker leverages their authenticated session token to send HTTP GET or POST requests to the internal API routes that serve comment data. Because the server does not cross-reference the user's role and permissions against the ownership of each individual comment record before returning the payload, the system inadvertently discloses restricted information. This is particularly dangerous in environments where Ghost is used for community building or intranet applications, as it undermines the fundamental trust model that relies on authenticated users to respect content boundaries. The flaw persists across versions from 5.9.0 up until but not including 6.44.1, indicating a systemic issue in how the comment service handles permission checks during this development cycle.
The operational impact of this vulnerability is significant for organizations relying on Ghost for secure community engagement or internal communications. Successful exploitation leads to the disclosure of restricted comment data, which can include personal opinions, private feedback, and potentially sensitive discussions that were not meant for public consumption by all registered members. This breach of confidentiality violates user privacy expectations and may expose individuals to harassment or reputational damage if their comments are viewed by unauthorized parties. Furthermore, this information leakage can facilitate further attacks; attackers could analyze the disclosed content to identify high-value targets within the community, gather intelligence on administrative workflows, or find additional vectors for social engineering. The ability to view restricted data effectively nullifies any privacy settings configured at the comment level, rendering features such as member-only comments or admin-moderated threads ineffective against authenticated insiders with malicious intent.
To mitigate this risk, immediate action is required by upgrading the Ghost installation to version 6.44.1 or later, where the input validation and access control mechanisms have been corrected to ensure that comment retrieval requests are strictly validated against user permissions. Administrators should also review their current deployment configurations to ensure no other services expose similar endpoints without proper authentication checks. In environments where upgrading is not immediately feasible due to compatibility constraints, implementing a Web Application Firewall with rules designed to detect anomalous access patterns to the comments API can provide temporary protection by blocking requests that attempt to retrieve data outside of expected parameter ranges or user contexts. Additionally, enabling comprehensive logging and monitoring for comment-related API calls allows security teams to detect potential exploitation attempts in real-time, facilitating rapid incident response if unauthorized access is observed. Regular audits of authentication and authorization logic across all custom integrations are recommended to prevent similar bypasses in other modules of the application.