Description

In JetBrains Datalore before 2026.4 code execution was possible in another user's computation via an init script upload race condition

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.9",
  "pubDate": "2026-11-06T17:17:21.823Z",
  "pubdate": "2026-11-06T17:17:21.823Z",
  "executiveSummary": "This vulnerability involves a race condition in JetBrains Datalore, present in versions prior to 2026.4, which allows for unauthorized arbitrary code execution within another user's computational environment.\nThe vulnerability is categorized as a race condition leading to improper privilege isolation and code execution.\nAn authenticated attacker can exploit the race window during the initialization phase of a workspace or computation session.\nBy manipulating the init script upload process, an attacker can inject malicious code that executes with the privileges of the target user's computation session.\nThe impact is significant, as it facilitates cross-user data exfiltration, unauthorized modification of computational notebooks, and potential escalation of privileges within the Datalore environment.\nThe attack requires the ability to interact with the platform's computation initialization workflow but does not necessarily require administrative privileges, representing a high risk to multi-tenant Datalore deployments.",
  "technicalDetails": "The vulnerability originates from a race condition existing during the handling of init scripts within JetBrains Datalore's computational infrastructure.\nDatalore allows users to define custom initialization scripts that are executed when a computation session is launched. The flaw exists in the mechanism that validates, stores, and subsequently executes these scripts during the container or process spin-up phase.\nThe race condition occurs between the point where the init script is uploaded or referenced and the point where the server environment initializes the script for the user's session. Specifically, the synchronization mechanism responsible for securing the temporary storage area where init scripts are placed before execution is insufficient.\nAn attacker can exploit this by initiating a legitimate computation session and simultaneously submitting a malformed or malicious init script modification. If the timing is precise, the attacker can replace the intended init script with a malicious payload after the initial security check has passed but before the execution environment loads the script into the target session.\nThis exploitation flow permits the attacker to achieve remote code execution within the context of a victim's computation container. Because these scripts are processed with the identity of the session owner, the attacker effectively bypasses isolation boundaries between different users on the same Datalore instance.\nTechnical requirements for exploitation include: 1) Access to the Datalore environment with the ability to trigger computation sessions; 2) The ability to influence the init script path or content; 3) Precise timing to win the race condition against the server's verification logic. The vulnerability resides within the workspace management and session initialization components of the Datalore backend. Once exploited, the attacker can execute arbitrary system commands, access environment variables, read sensitive user files (such as database credentials or API keys), and interact with the user's notebook data.\nThe vulnerability affects all versions of JetBrains Datalore prior to 2026.4. Post-exploitation, an attacker can maintain persistence within the user's session, potentially pivoting to other resources accessible via the computational environment's network or file system."
}