Description

Ghost is a Node.js content management system. From 5.9.0 until 6.44.1, an input validation issue allowed members to access comments they were not authorized to access. This issue is fixed in version 6.44.1.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "6.5",
  "pubDate": "2026-10-05T20:17:16.320Z",
  "pubdate": "2026-10-05T20:17:16.320Z",
  "executiveSummary": "This vulnerability is an improper input validation flaw affecting the Ghost content management system.\nThe issue permits authenticated members to access comments they are not authorized to view, leading to an unauthorized information disclosure.\nThe vulnerability affects Ghost versions 5.9.0 through 6.44.1.\nThe root cause is a failure in the application's access control logic to properly validate member permissions against requested comment resources.\nAn attacker must possess a valid member account to exploit this vulnerability, as the flaw resides within the member-facing API or controller handling comment retrieval.\nSuccessful exploitation results in unauthorized access to restricted or private comments, potentially exposing sensitive member data or private discussions.\nThe risk implication is high for platforms relying on granular comment visibility, as the vulnerability bypasses intended authorization boundaries.\nThe issue is remediated in version 6.44.1, which introduces corrected input validation and authorization checks.",
  "technicalDetails": "The vulnerability resides in the Ghost comment retrieval mechanism, which failed to properly enforce access controls during the processing of member-originated requests.\nIn affected versions (5.9.0 through 6.44.1), the API endpoint responsible for serving comments did not adequately validate the authorization context of the requesting user against the requested resource's metadata.\nThe root cause is attributed to an input validation defect where the system failed to verify whether the authenticated member possessed the necessary privileges or organizational relationship required to access specific comment threads.\nThe attack flow begins when an authenticated member submits a request for comment data to the Ghost server. Due to insufficient validation, the server's backend logic fails to perform a secondary authorization check to determine if the requester is permitted to see the specified comment object.\nBecause the server assumes the identity of the member is sufficient to bypass resource-level checks, it proceeds to query the database and return the requested comment data in the JSON response, regardless of the user's actual access rights.\nExploitation requires the attacker to be authenticated as a member. The attacker can manipulate the request parameters (e.g., modifying a comment ID or resource identifier) to query unauthorized endpoints. The system's failure to enforce object-level authorization allows the attacker to traverse and view comments intended for other users, private groups, or internal site management contexts.\nThe vulnerable component is the member authentication and comment service layer. Since the flaw is logical in nature—stemming from a lack of validation rather than a syntax error—it is invisible to standard signature-based security tools.\nThe post-exploitation impact includes the exposure of private metadata, potentially sensitive discussions within comment threads, and the bypass of community visibility settings. Given that Ghost manages content and community interactions, this unauthorized access poses a significant privacy risk and threatens the integrity of member-to-member interactions.\nThe remediation, effective in version 6.44.1, implements mandatory authorization verification within the comment controller, ensuring that every request for comment content is checked against the user's permission set before the resource is serialized and returned to the client."
}