CVE-2026-9255 - Tool Execution Without Authorization via Piped Stdin in Kiro CLI

unknownCVE-2026-9255

Bulletin ID: 2026-035-AWS Scope: AWS Content Type: Important (requires attention) Publication Date: 05/22/2026 09:45 AM PDT Description: Kiro CLI is a command-line AI coding assistant that enables developers to interact with AI models to execute code, manage files, and run shell commands. We identified CVE-2026-9255, an issue where missing input source validation in the tool authorization prompt could allow a local actor to execute arbitrary tools, including shell commands, without user approval by crafting content that is piped to kiro-cli via stdin. Impacted versions: kiro-cli prior to 1.28.0 Please refer to the article below for the most up-to-date and complete information related to this AWS Security Bulletin.

CSIRTS triage

vendor: AWS product: Kiro CLI Authentication bypassaffected: < 1.28.0

What: Missing input source validation could allow local actors to execute arbitrary tools without user approval.
Who is affected: Users of Kiro CLI versions prior to 1.28.0.
Urgency: Remediation is urgent as it allows unauthorized tool execution.
Action: Upgrade Kiro CLI to version 1.28.0 or later.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: AWS Security Bulletins (INTL · vendor-psirt · site)
Severity: unknown
Published: 2026-08-20
Exploitation: Not in CISA KEV at last sync

Original advisory: https://aws.amazon.com/security/security-bulletins/rss/2026-035-aws/

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-92550.12% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 2% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-9255	coverage & exploitation status	NVD · CVE.org

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