Why Does AWS Patch Kiro IDE to Stop Windows Executable Hijacking in Projects?

Amazon Web Services disclosed two vulnerabilities in its Kiro development tools that allow arbitrary code execution on Windows systems. The flaws, tracked as CVE-2026-18656 and CVE-2026-18657, stem from how the software resolves executables within project directories. According to the AWS Security Bulletin published on August 4, 2026, an attacker can place a malicious executable in a project folder. When a local user opens that directory, the tool runs the planted file before checking the system PATH, bypassing standard security controls.

Which versions are vulnerable?

The issue impacts Kiro IDE for Windows versions 1.0.0 through 1.0.212. These versions of the agentic IDE and command-line interface fail to properly validate executable paths within untrusted project directories. Users running any build within this range are exposed to the risk of arbitrary code execution if they open a crafted project folder. The vulnerability exists because the application prioritizes local directory contents over the established system environment variables during execution resolution.

How does the attack work?

An actor creates a maliciously crafted project directory containing a planted executable. According to the advisory, when a local user opens this directory in the affected Kiro software, the application resolves the executable from the untrusted location. This resolution happens before the system checks the standard PATH variable. Consequently, the attacker’s code runs with the privileges of the user opening the project, allowing for arbitrary code execution without requiring additional user interaction beyond opening the folder.

Who reported these flaws?

Edo Maland reported the issue affecting the Kiro IDE through the coordinated vulnerability disclosure process. For the Kiro CLI vulnerability, AWS credited a team from Compass Security. This group includes Emanuele Barbeno, Cyrill Bannwart, Urs Mueller, Lukasz D, and Yves Bieri. Both reports were handled through AWS’s coordinated disclosure channels. The company thanked these researchers for identifying the uncontrolled search path elements that could lead to code execution in the Windows environment.

What is the fix status?

AWS has addressed these issues in recent releases. Kiro IDE version 1.0.228 includes the necessary patches for the IDE vulnerability. The Kiro CLI version 2.10.0 resolves the corresponding issue in the command-line interface. The bulletin recommends upgrading to these latest versions immediately. Additionally, AWS advises users to ensure any forked or derivative code incorporates these new fixes to maintain security against this specific execution path manipulation.

What analysts watch for

Teams usually monitor for unexpected executable files appearing in project directories or source code repositories. Analysts check whether applications prioritize local file resolution over system environment variables during startup or file opening events. They examine process creation logs for binaries launched from non-standard paths, particularly those outside the system PATH or known application directories. Security teams also look for scripts or tools that automatically execute code when a folder is opened in an IDE, as this behavior can mask malicious activity.

Background: Vulnerability disclosure policies

A vulnerability disclosure policy defines how external researchers report security flaws. It establishes safe harbor protections, clarifies communication channels, and sets expectations for response times. This structure prevents accidental legal conflicts while ensuring critical defects reach engineering teams before exploitation. Clear policies reduce noise and prioritize high-risk issues effectively.

Read the full guide: Vulnerability Disclosure Policies: 9 FAQs Answered for Clear Coordination

What to do and how to stay safe: Kiro IDE

• Upgrade Kiro IDE to version 1.0.228 or later to patch the executable resolution flaw.
• Update Kiro CLI to version 2.10.0 or later to address the corresponding vulnerability.
• Audit project directories for unexpected executable files before opening them in the IDE.
• Review forked or derivative code to ensure it incorporates the latest security fixes from AWS.

Step-by-step guide: Patch Management: Why Updates Fail and How to Fix It

General security guidance from the Sandbox Dispatch newsroom. It is not confirmed advice from the organisations named in this story.

Frequently asked questions

What is CVE-2026-18656?

It is a vulnerability in Kiro IDE for Windows that allows arbitrary code execution via an uncontrolled search path element in untrusted project directories.

Does this affect Linux or macOS?

The advisory specifically states the issue affects Kiro IDE and CLI on Windows. No other operating systems are mentioned in the bulletin.

Who should I contact for questions?

AWS directs security questions and concerns to [email protected], as stated in the official security bulletin.