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

> A local attacker can execute arbitrary tools and shell commands without user approval by piping crafted content to Kiro CLI stdin.

- **Severity:** High 8.4 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 22 May 2026
- **Updated:** 23 May 2026
- **Also known as:** GHSA-cv6r-hx5v-c4m6

## What is CVE-2026-9255?

CVE-2026-9255 is a high-severity missing authorization vulnerability in AWS Kiro CLI, published on 22 May 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

Missing input source validation in the tool authorization prompt in Kiro CLI before 1.28.0 allows a local attacker to execute arbitrary tools, including shell commands, without user approval by crafting content that is piped to kiro-cli via stdin.

We recommend you to upgrade to kiro-cli version 1.28.0 or later.

Weakness: CWE-862 (Missing Authorization)

## Which versions are affected by CVE-2026-9255?

It affects 1 product.


Products: Amazon Kiro Cli.

## How do I fix CVE-2026-9255?

No fix has been published for CVE-2026-9255 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-9255 being exploited?

There is no known exploitation of CVE-2026-9255 in the wild and no public exploit code.

## Other vulnerabilities in AWS Kiro CLI

- [CVE-2026-18657](https://insights.sbomify.com/CVE-2026-18657/): Executable Resolution from Untrusted Project Directory in Kiro CLI on Windows (high 8.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-9255 and fix it if it is affected.

What it is: CVE-2026-9255 is a high-severity missing authorization vulnerability in AWS Kiro CLI, published on 22 May 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-9255 in the wild and no public exploit code.

Affected product: AWS Kiro CLI. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-9255/ (Markdown: https://insights.sbomify.com/CVE-2026-9255/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-9255
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-9255
- OSV: https://osv.dev/vulnerability/CVE-2026-9255

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-9255/
Summaries are generated and may contain mistakes; the official description above is the record.