CVE-2026-86504 Overview
CVE-2026-86504 affects JetBrains IntelliJ IDEA versions before 2026.2.2. The IDE fails to prompt for project-trust confirmation before building a Dev Container. An attacker who supplies a crafted project can trigger host-level code execution when a developer opens the project. The flaw is categorized under [CWE-829] (Inclusion of Functionality from Untrusted Control Sphere).
Exploitation requires local access and user interaction, such as opening a malicious repository in IntelliJ IDEA. Successful exploitation yields high impact to confidentiality, integrity, and availability on the developer host.
Critical Impact
Opening an untrusted project in a vulnerable IntelliJ IDEA build can execute attacker-controlled code on the developer workstation without a trust prompt.
Affected Products
- JetBrains IntelliJ IDEA versions prior to 2026.2.2
- Dev Containers feature within IntelliJ IDEA
- Developer workstations that open untrusted projects containing Dev Container definitions
Discovery Timeline
- 2026-09-07 - CVE-2026-86504 published to the National Vulnerability Database (NVD)
- 2026-09-09 - Record last modified in NVD
Technical Details for CVE-2026-86504
Vulnerability Analysis
JetBrains IntelliJ IDEA supports Dev Containers, a specification that lets projects declare a containerized development environment through a .devcontainer/devcontainer.json file. Building the container typically executes lifecycle scripts, Dockerfile instructions, and post-create commands defined in the project.
IntelliJ IDEA normally shields users from untrusted projects through a project-trust confirmation dialog. In affected releases, the Dev Container build path bypasses this confirmation. The IDE proceeds to construct the container using project-supplied instructions before the developer approves the project as trusted.
Because container build steps invoke shell commands, package installers, and arbitrary binaries on the host, the missing trust check converts a passive "open project" action into local code execution on the developer host.
Root Cause
The root cause is a missing trust gate in the Dev Container build workflow. The IDE integrates functionality from an untrusted control sphere (the project's Dev Container configuration) without validating that the user has designated the project as trusted, matching the [CWE-829] weakness pattern.
Attack Vector
An attacker distributes a repository, archive, or shared workspace that contains a malicious Dev Container definition. The victim opens the project in a vulnerable IntelliJ IDEA build. The IDE builds the Dev Container without a trust prompt, executing attacker-controlled commands with the developer's privileges. Delivery channels include public source hosting, supply-chain injection into forks, and phishing attachments referencing sample projects.
Refer to the JetBrains Security Issues Fixed page for vendor technical details.
Detection Methods for CVE-2026-86504
Indicators of Compromise
- Unexpected docker build, docker run, or podman invocations spawned as child processes of IntelliJ IDEA (idea64.exe, idea, or idea.sh)
- Execution of postCreateCommand, onCreateCommand, or initializeCommand scripts referenced from newly cloned repositories
- Outbound network connections initiated by container build steps to previously unseen hosts shortly after a project is opened
- Newly created .devcontainer/ directories in repositories associated with subsequent host process anomalies
Detection Strategies
- Hunt for IntelliJ IDEA process trees that spawn container runtimes or shell interpreters within seconds of project open events
- Correlate file-open telemetry for devcontainer.json with subsequent execution of sh, bash, cmd.exe, or powershell.exe under the IDE process ancestry
- Flag installations of IntelliJ IDEA reporting versions earlier than 2026.2.2 through software inventory data
Monitoring Recommendations
- Ingest endpoint process and file telemetry into a centralized data lake to enable retroactive hunts across developer fleets
- Alert on first-time execution of Dev Container lifecycle commands per user and per repository
- Track cloning activity from unfamiliar Git remotes followed by container build activity on developer workstations
How to Mitigate CVE-2026-86504
Immediate Actions Required
- Upgrade IntelliJ IDEA to version 2026.2.2 or later on all developer workstations
- Inventory endpoints running vulnerable IntelliJ IDEA builds and prioritize systems that handle third-party or open-source projects
- Instruct developers to avoid opening untrusted repositories in IntelliJ IDEA until the patch is deployed
Patch Information
JetBrains addressed the issue in IntelliJ IDEA 2026.2.2 by enforcing the project-trust confirmation before Dev Container builds. The fix is listed on the JetBrains Security Issues Fixed page. Apply the update through the JetBrains Toolbox App or the in-product update mechanism.
Workarounds
- Disable or uninstall the Dev Containers plugin until upgrading to 2026.2.2
- Review any repository for a .devcontainer/ directory before opening it in the IDE, and inspect referenced Dockerfiles and lifecycle commands
- Open unknown projects inside an isolated virtual machine that has no access to production credentials or source repositories
- Restrict local Docker or Podman daemon access to trusted users on developer hosts
# Verify installed IntelliJ IDEA version on Linux/macOS
idea --version
# Confirm the build number is 2026.2.2 or later before opening untrusted projects
# On Windows, check Help > About in the IDE or inspect the product-info.json
# under the IntelliJ IDEA installation directory
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
