CVE-2026-18656 Overview
CVE-2026-18656 is an uncontrolled search path element vulnerability [CWE-427] affecting Kiro IDE on Windows before version 1.0.228. The flaw allows arbitrary code execution when a local user opens a maliciously crafted project directory. An attacker plants an executable inside the project folder, and Kiro IDE resolves that executable through its uncontrolled search path, bypassing the workspace trust protections designed to prevent this class of attack.
The vulnerability is tracked in AWS Security Bulletin 2026-074 and addressed in the Kiro Dev Changelog patch 1.0.228.
Critical Impact
A single act of opening an untrusted project directory in a vulnerable Kiro IDE build results in arbitrary code execution in the context of the local user, undermining workspace trust guarantees.
Affected Products
- Kiro IDE for Windows, all versions prior to 1.0.228
- Local Windows user sessions running vulnerable Kiro IDE builds
- Development workstations that open third-party or shared project directories
Discovery Timeline
- 2026-08-04 - CVE-2026-18656 published to NVD
- 2026-08-06 - Last updated in NVD database
Technical Details for CVE-2026-18656
Vulnerability Analysis
The vulnerability stems from an uncontrolled search path element [CWE-427] in how Kiro IDE resolves executables on Windows. When a user opens a project directory, Kiro IDE searches for supporting binaries without adequately constraining the search order. An attacker who controls the directory contents can place an executable with a name Kiro IDE looks up during initialization. Windows resolves that name against the project directory before trusted system locations, and the malicious binary runs in the user's session.
Workspace trust is intended to gate execution of untrusted project content until the user explicitly approves it. In this case, the search-path resolution occurs before or outside the trust check, so simply opening the folder is sufficient to trigger execution.
Root Cause
The root cause is insecure executable lookup logic that includes the project directory as an implicit search location. Combined with a workspace trust check that does not cover the affected code path, the loader treats attacker-controlled binaries as legitimate helpers. This is a classic instance of CWE-427: Uncontrolled Search Path Element.
Attack Vector
Exploitation requires local user interaction: the victim must open a malicious project directory in Kiro IDE. The attacker delivers the directory through common channels such as Git repositories, archive downloads, shared network folders, or removable media. No authentication to the target system is needed beyond the victim's own session, and no additional privileges are required to plant the payload inside the project. Code execution runs with the privileges of the user who opened the directory.
Because the trigger is directory open, this vector aligns with supply-chain style attacks against developers, where a poisoned repository serves as the delivery mechanism.
Detection Methods for CVE-2026-18656
Indicators of Compromise
- Unexpected executables such as .exe, .dll, or .bat files present at the root of project directories opened by Kiro IDE.
- Child processes spawned by the Kiro IDE process tree that originate from user project paths rather than the Kiro install directory.
- Outbound network connections initiated shortly after a Kiro IDE workspace open event.
Detection Strategies
- Hunt for process creation events where the parent is a Kiro IDE binary and the child image path resides under a user's project or repository folder.
- Alert on Kiro IDE versions below 1.0.228 reported through software inventory or endpoint telemetry.
- Correlate Git clone or archive extraction events with subsequent Kiro IDE launches referencing the same directory.
Monitoring Recommendations
- Log and review Windows process creation (Event ID 4688) with command-line auditing enabled on developer workstations.
- Monitor file-write events that place executable content into repositories cloned from external sources.
- Track Kiro IDE version compliance across the developer fleet and flag hosts still running vulnerable builds.
How to Mitigate CVE-2026-18656
Immediate Actions Required
- Upgrade Kiro IDE to version 1.0.228 or later on all Windows endpoints.
- Inventory developer workstations and identify hosts running vulnerable Kiro IDE builds.
- Instruct developers not to open untrusted project directories in Kiro IDE until the update is applied.
Patch Information
AWS released the fix in Kiro IDE 1.0.228. Refer to the Kiro Dev Changelog patch 1.0.228 for release notes and to AWS Security Bulletin 2026-074 for the vendor advisory. Users should upgrade directly to 1.0.228 or higher; no partial mitigation is offered by intermediate builds.
Workarounds
- Only open project directories obtained from trusted, verified sources until patching is complete.
- Scan repositories for unexpected executable files before opening them in Kiro IDE.
- Run Kiro IDE under a low-privileged Windows account to limit the impact of code execution.
- Store development projects on paths that block execution via Windows AppLocker or Software Restriction Policies.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
