CVE-2026-86505: IntelliJ IDEA Information Disclosure Flaw

CVE-2026-86505 Overview

CVE-2026-86505 is an information disclosure vulnerability in JetBrains IntelliJ IDEA versions prior to 2026.2.2. The IDE fails to perform a project-trust check before communicating with the JetBrains Marketplace. As a result, project metadata is leaked to the marketplace service without user consent for untrusted projects.

The issue is categorized under [CWE-201] (Insertion of Sensitive Information Into Sent Data). Exploitation requires the local user to open an untrusted project in the affected IDE.

Critical Impact
Opening an untrusted project in a vulnerable version of IntelliJ IDEA transmits project metadata to JetBrains Marketplace without the user first confirming trust in the project.

Affected Products

JetBrains IntelliJ IDEA versions prior to 2026.2.2
Projects opened without the project-trust confirmation prompt
Environments that reach JetBrains Marketplace endpoints from the IDE

Discovery Timeline

2026-09-07 - CVE-2026-86505 published to the National Vulnerability Database
2026-09-08 - Last updated in NVD database

Technical Details for CVE-2026-86505

Vulnerability Analysis

IntelliJ IDEA implements a project-trust mechanism that gates functionality when a user opens a project from an unknown source. Trusted projects can execute build scripts, resolve dependencies, and reach external services. Untrusted projects should be restricted to read-only inspection.

In versions prior to 2026.2.2, the code path that queries JetBrains Marketplace does not consult the project-trust state. When a user opens a project, the IDE transmits project metadata to the marketplace service before the trust prompt is resolved. The disclosure is limited to metadata handled by the marketplace integration and does not involve source code contents.

Root Cause

The root cause is a missing authorization check on the marketplace client code path. The trust boundary that separates untrusted projects from network-enabled features was not enforced for marketplace requests. This aligns with [CWE-201], where sensitive information is inserted into data sent to an external party without appropriate control.

Attack Vector

The attack vector is local and requires user interaction. An attacker crafts a project and delivers it to a target developer through a repository, archive, or shared workspace. When the developer opens the project in a vulnerable IntelliJ IDEA build, the IDE contacts JetBrains Marketplace and includes project metadata in the request. The attacker does not receive the data directly; the disclosure is to the marketplace endpoint. Refer to the JetBrains Security Issues Resolved advisory for the fix description.

Detection Methods for CVE-2026-86505

Indicators of Compromise

Outbound HTTPS connections from idea64.exe, idea, or JetBrains Toolbox processes to JetBrains Marketplace hostnames immediately after opening a newly cloned or downloaded project.
IDE logs under the JetBrains configuration directory showing marketplace queries executed before a project-trust decision was recorded.
Presence of IntelliJ IDEA installations reporting a version string below 2026.2.2.

Detection Strategies

Inventory developer endpoints for IntelliJ IDEA builds and flag any version earlier than 2026.2.2.
Correlate process telemetry from the IDE with network telemetry to identify marketplace calls that occur without a corresponding trust-prompt user event.
Review endpoint DLP and proxy logs for outbound project metadata originating from JetBrains IDE processes on hosts where untrusted projects were opened.

Monitoring Recommendations

Alert on IntelliJ IDEA processes initiating marketplace requests shortly after project directory creation or Git clone events.
Track version drift across developer workstations to ensure the 2026.2.2 patch remains installed after IDE auto-updates.
Maintain audit logging on proxy egress for JetBrains domains to reconstruct what metadata left the environment during the exposure window.

How to Mitigate CVE-2026-86505

Immediate Actions Required

Upgrade IntelliJ IDEA to version 2026.2.2 or later on all developer workstations.
Confirm JetBrains Toolbox is configured to deliver the patched build and disable pinning to older releases.
Instruct developers to decline the trust prompt for any project of unknown origin until the upgrade completes.

Patch Information

JetBrains resolved the missing project-trust check in IntelliJ IDEA 2026.2.2. The fix enforces the trust boundary on the marketplace client path so that project metadata is no longer transmitted before the user grants trust. Full details are published in the JetBrains Security Issues Resolved bulletin.

Workarounds

Open unknown projects in a sandboxed virtual machine that has no network egress to JetBrains Marketplace endpoints.
Block outbound access to JetBrains Marketplace hostnames at the proxy for hosts that cannot be patched immediately.
Use the IDE in offline mode when reviewing untrusted code, then upgrade to 2026.2.2 before restoring network access.

bash

# Configuration example: block marketplace egress at the host firewall on Linux
sudo iptables -A OUTPUT -m owner --uid-owner developer \
  -d plugins.jetbrains.com -j REJECT
sudo iptables -A OUTPUT -m owner --uid-owner developer \
  -d downloads.marketplace.jetbrains.com -j REJECT