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

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-02 · updated 2026-07-24
Weakness: CWE-79

Description

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 potentially damaging crafted color theme name when a local user opens the workspace. This issue requires the user to trust the workspace when prompted. To remediate this issue, users should upgrade to version 0.8.140.

Affected products

AWS Kiro IDE: from 0.1 before 0.8.140 — fixed in 0.8.140

How to fix

Upgrade to a fixed version: AWS Kiro IDE 0.8.140. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-5429 or the next vulnerability affects your stack