CVE-2026-86504: 
JetBrains IntelliJ IDEA vulnerability analysis and mitigation

CVE-2026-86504 is a local code execution vulnerability in JetBrains IntelliJ IDEA caused by missing project-trust confirmation before building a Dev Container, which allows host-level code execution. It affects all IntelliJ IDEA versions before 2026.2.2 and was disclosed on September 7, 2026. The vulnerability carries a CVSS v3.1 base score of 7.8 (High) (GitHub Advisory, JetBrains).

The root cause is classified as CWE-829 (Inclusion of Functionality from Untrusted Control Sphere): IntelliJ IDEA fails to prompt the user for project-trust confirmation before initiating a Dev Container build, allowing untrusted project configurations (e.g., a malicious devcontainer.json or associated Dockerfile) to execute arbitrary code at the host level. The attack vector is local, requires no privileges, but does require user interaction — specifically, a user opening and triggering a Dev Container build from an untrusted project. This is consistent with supply-chain or social-engineering scenarios where a developer is tricked into opening a malicious repository (GitHub Advisory, JetBrains).

Successful exploitation grants an attacker host-level code execution with the privileges of the user running IntelliJ IDEA, resulting in high confidentiality, integrity, and availability impact. An attacker could read sensitive files, modify the host filesystem, install persistent malware, or pivot to other systems accessible from the developer's workstation. The scope is particularly significant in developer environments where credentials, source code, and internal network access are commonly available (GitHub Advisory).

There is no public proof-of-concept exploit and no evidence of in-the-wild exploitation as of the disclosure date (GitHub Advisory). The EPSS score is approximately 0.128% (3rd percentile), indicating a low near-term exploitation probability. The vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog. Exploitation is not automatable and requires user interaction, limiting opportunistic mass exploitation.

1. Craft a malicious repository: Create a repository containing a Dev Container configuration (e.g., .devcontainer/devcontainer.json) that references a malicious Dockerfile or postCreateCommand designed to execute arbitrary code on the host.
2. Deliver the repository to the target: Distribute the malicious repository via a public platform (e.g., GitHub), phishing link, or supply-chain compromise to lure a developer into cloning it.
3. Induce the victim to open the project in IntelliJ IDEA: Social engineering or a convincing README can prompt the developer to open the project in a vulnerable version of IntelliJ IDEA (before 2026.2.2).
4. Trigger Dev Container build: The victim initiates or IntelliJ IDEA automatically suggests building the Dev Container. Due to the missing project-trust confirmation, the IDE proceeds without verifying the project's trustworthiness.
5. Achieve host-level code execution: The malicious container build instructions execute arbitrary commands on the host system with the privileges of the IDE user, enabling data exfiltration, credential theft, or persistence (GitHub Advisory).

• File System: Unexpected files created in the user's home directory or project directory during or after a Dev Container build; new or modified .devcontainer/devcontainer.json or Dockerfile with suspicious RUN, CMD, or postCreateCommand entries.
• Process: Unusual child processes spawned by IntelliJ IDEA or Docker daemon (e.g., curl, wget, bash, python, nc) during a Dev Container build; unexpected network connections initiated by container build processes.
• Network: Outbound connections to unknown external hosts from the developer workstation during or shortly after a Dev Container build, particularly to uncommon ports or IP ranges.
• Logs: IntelliJ IDEA logs (idea.log) showing Dev Container build activity for recently opened, untrusted projects; Docker daemon logs (/var/log/docker.log or journalctl -u docker) reflecting unexpected image pulls or command execution.

Upgrade JetBrains IntelliJ IDEA to version 2026.2.2 or later, which introduces the required project-trust confirmation before building a Dev Container (JetBrains, GitHub Advisory). Until patching is possible, restrict or disable Dev Container usage within the IDE, and implement organizational policies requiring manual review of .devcontainer configurations before opening unfamiliar repositories. Developers should exercise caution when opening projects from untrusted or unknown sources.

Community discussion was observed on Bluesky and Mastodon shortly after disclosure, with security-focused accounts noting the risk to developer workstations (GitHub Advisory). A blog post on Bulwark Black discussed JetBrains IDE Dev Container trust boundary defenses in the context of this vulnerability. Overall community sentiment reflects moderate concern, given the targeted nature of the attack and the availability of a patch.