Kiro IDE versions prior to 0.8.140 contain a cross‑site scripting flaw in the Kiro Agent webview. Unsanitized color theme names that a workspace developer can provide are written into a dynamically generated web page. An attacker may create a malicious color theme name containing script payloads. When a local user opens a workspace that includes such a theme, the webview will execute the script in the context of the application, allowing arbitrary code to run on the user’s machine. This vulnerability falls under CWE‑79 and can potentially compromise confidentiality, integrity, and availability of the affected system.

The affected product is Kiro IDE by AWS. All installations running a version earlier than 0.8.140 are vulnerable. No other vendor or product is affected according to the available data.

The vulnerability carries a CVSS base score of 7.1, indicating a high severity. EPSS data is not available and the issue is not listed in CISA's KEV catalog. Because the flaw requires local user interaction (opening a workspace) but does not require prior authentication, any local user could be coerced, presenting a significant risk. An attacker would need to supply a malicious color theme and get a user to load it; once the user does so, the attacker can execute arbitrary code. The attack vector is effectively remote, luring the user into opening a malicious workspace.