Description

In JetBrains Datalore before 2026.4 improper authorisation allowed notebook viewers to modify files

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.4",
  "pubDate": "2026-11-06T11:17:07.440Z",
  "pubdate": "2026-11-06T11:17:07.440Z",
  "executiveSummary": "This vulnerability involves an improper authorization flaw within JetBrains Datalore, specifically affecting the notebook viewing component.\nThe vulnerability allows users with 'viewer' permissions—who should be restricted to read-only access—to perform unauthorized modifications to files within the Datalore environment.\nThis represents a significant security oversight, as it permits low-privileged users to bypass access control mechanisms and manipulate sensitive data or code environments without explicit authorization.\nThe flaw affects all versions of JetBrains Datalore prior to 2026.4.\nThe risk implications include potential data integrity loss, unauthorized code injection, and unauthorized modification of project resources.\nAttackers can leverage this vulnerability to alter notebook contents, potentially leading to unauthorized execution or data corruption within the project scope, even without elevated administrative privileges.",
  "technicalDetails": "The root cause of this vulnerability lies in an inadequate authorization check mechanism implemented within the notebook viewer interface of JetBrains Datalore. In a typical secure environment, the application backend should perform server-side validation to ensure that any request to modify, delete, or overwrite files is validated against the requester's session permissions.\nIn affected versions of Datalore, the application fails to correctly enforce restrictive access controls for users granted the 'viewer' role when they interact with the file management or notebook saving endpoints. Consequently, the backend incorrectly processes modification requests submitted by users who lack the 'editor' or 'administrator' roles.\nThe attack flow commences with an authenticated attacker, possessing a 'viewer' privilege, interacting with the Datalore notebook workspace. By identifying the specific API endpoints or internal application functions responsible for file operations—typically those associated with save operations, write requests, or notebook state synchronization—the attacker can craft malicious requests.\nBecause the server-side authorization logic is flawed, it treats the incoming request as valid, failing to perform the necessary verification of the user's write-access permissions. The application proceeds to execute the write command, allowing the 'viewer' to modify, append to, or overwrite files that reside within the project directory.\nThis vulnerability allows for the silent manipulation of code or data files, which can have downstream consequences. For example, if a viewer modifies a notebook file that is intended for later execution by an administrator or another authorized user, the attacker can execute arbitrary code within the context of that user's session once the modified file is opened or executed.\nThis privilege escalation mechanism essentially circumvents the intent of the role-based access control (RBAC) model implemented in Datalore. The vulnerability resides within the application's request-handling component, which governs file system interactions. Because this occurs at the application layer, no special network exposure is required beyond standard connectivity to the Datalore instance, provided the attacker has an active, authenticated session with 'viewer' access."
}