PatchSiren cyber security CVE debrief

CVE-2026-5429 AWS CVE debrief

CVE-2026-5429 is a high-severity vulnerability in the Kiro Agent webview of Kiro IDE versions prior to 0.8.140. The issue arises from unsanitized input during web page generation, allowing a remote unauthenticated threat actor to execute arbitrary code via a crafted color theme name when a local user opens the workspace. This requires the user to trust the workspace when prompted. The vulnerability has a CVSS score of 7.1, indicating high severity. Users and administrators should prioritize patching to prevent potential exploitation.

Vendor: AWS
Product: Kiro IDE
CVSS: HIGH 7.1
CISA KEV: Not listed in stored evidence
Original CVE published: 2026-04-02
Original CVE updated: 2026-07-24
Advisory published: 2026-04-02
Advisory updated: 2026-07-24

Who should care

Users of Kiro IDE versions prior to 0.8.140 should be aware of this vulnerability and take immediate action to upgrade to the latest version. Additionally, administrators and security teams responsible for managing Kiro IDE installations should prioritize patching to prevent potential exploitation and review their current security controls.

Technical summary

The vulnerability exists in the Kiro Agent webview of Kiro IDE, specifically in the handling of color theme names. An attacker can exploit this by providing a crafted theme name that, when opened by a local user, allows for arbitrary code execution. The CVSS score for this vulnerability is 7.1, indicating a high severity level. This issue requires user interaction, as the user must trust the workspace when prompted.

Defensive priority

High

Recommended defensive actions

Upgrade Kiro IDE to version 0.8.140 or later
Verify that all Kiro IDE installations are running the patched version
Monitor Kiro IDE installations for any suspicious activity
Restrict workspace trust prompts to only trusted sources
Review compensating controls for exposed systems while remediation is scheduled and verified
Check relevant monitoring, detection, and logs for exposed assets that need extra review
Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record was published on 2026-04-02T19:21:37.083Z and last modified on 2026-07-24T20:10:00.147Z. The NVD entry is currently awaiting analysis. Evidence is limited to public sources and may not reflect the full scope or impact of this vulnerability. Defenders should verify affected systems and review official advisories for specific guidance.

Sources and references

Verified primary and authoritative sources

CVE-2026-5429 CVE Program record
Publisher, destination, and source semantics verified

URL: https://www.cve.org/CVERecord?id=CVE-2026-5429

CVE Program - Official CVE Program record with source-provided CVE metadata.
CVE-2026-5429 NVD vulnerability detail
Publisher, destination, and source semantics verified

URL: https://nvd.nist.gov/vuln/detail/CVE-2026-5429

NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Source reference
Unverified legacy reference

URL: https://aws.amazon.com/security/security-bulletins/2026-012-aws/

ff89ba41-3aa1-4d27-914a-91399e9639e5
Source reference
Unverified legacy reference

URL: https://kiro.dev/changelog/ide/0-8/

ff89ba41-3aa1-4d27-914a-91399e9639e5

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.