# CVE-2026-123281: JetBrains Datalore code execution in sidecar container via mount broker

Source: https://junglewise.ai/threats/cve-2026-123281-in-jetbrains-datalore-before-2026-4-notebook-code-could-execute  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-06. Updated: 2026-11-06  
License: CC BY 4.0 with a link back

CVE-2026-123281 · Severity: high · CVSS 7.5 · Published 2026-11-06

JetBrains Datalore is a collaborative data science notebook platform. A flaw in its mount broker component allows notebook code to execute arbitrary commands within the sidecar container, potentially exposing data or enabling further attacks on the underlying infrastructure.

Technologies: [Jetbrains Datalore](https://junglewise.ai/threats/technologies/datalore). Vendors: [Jetbrains](https://junglewise.ai/threats/vendors/jetbrains).

## Quick answers

**Is CVE-2026-123281 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-123281 being exploited in the wild.

**How severe is CVE-2026-123281?** High severity, with a CVSS score of 7.5, published 6 November 2026.

**Which products and versions are affected?** Jetbrains Datalore before 2026.4.

**Is there a fix for CVE-2026-123281?** Yes: fixed in Datalore 2026.4. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-123281 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-123281?** Check whether you run Jetbrains Datalore at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in Datalore 2026.4

## Technical details

The vulnerability allows notebook code to execute commands in the sidecar container through improper validation in the mount broker. This is a privilege escalation or container escape scenario where code running in the notebook context gains access to execute commands outside its intended sandbox. An attacker with the ability to run notebook code can exploit this to escape the notebook container.

## Affected products

- JetBrains Datalore before 2026.4

## Timeline

- 2026-11-06: disclosed

## References

- [https://www.jetbrains.com/privacy-security/issues-fixed/](https://www.jetbrains.com/privacy-security/issues-fixed/)

## Related threats

- [JetBrains Datalore SSH private key exposure in Git backup](https://junglewise.ai/threats/cve-2026-123836-in-jetbrains-datalore-before-2026-4-workspace-collaborators)
- [JetBrains Datalore code execution via init script race condition](https://junglewise.ai/threats/cve-2026-123835-in-jetbrains-datalore-before-2026-4-code-execution-was-possible)
- [JetBrains Datalore improper scope validation in database tasks](https://junglewise.ai/threats/cve-2026-123834-in-jetbrains-datalore-before-2026-4-improper-scope-validation-in)
- [JetBrains Datalore improper owner validation allowing workspace data access](https://junglewise.ai/threats/cve-2026-123291-in-jetbrains-datalore-before-2026-4-improper-owner-validation)
- [JetBrains Datalore information disclosure in public report endpoint](https://junglewise.ai/threats/cve-2026-123290-in-jetbrains-datalore-before-2026-4-hidden-notebook-code-was)