CVE-2026-5429 - Kiro IDE Webview Cross-Site Scripting via Workspace Color Theme

Bulletin ID: 2026-012-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 2026/04/02 11:30 AM PDT Description: Kiro IDE is an agentic development environment that makes it easy for developers to ship real engineering work with the help of AI agents. We identified CVE-2026-5429, where unsanitized input during web page generation in the Kiro Agent webview in Kiro IDE before version 0.8.140 allows a remote unauthenticated threat actor to execute arbitrary code via a maliciously crafted color theme name when a local user opens the workspace. This issue requires the user to trust the workspace when prompted. Impacted versions: Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.