CVE-2026-9255

Arbitrary tool execution via piped approval input

Published May 22, 2026 · Updated May 22, 2026

Missing authorization in Kiro CLI before 1.28.0 allows local users to execute arbitrary tools through content piped over standard input. The tool authorization prompt consumes bytes from the same redirected input stream as untrusted prompt content without validating their source. Exploitation requires a user to pipe attacker-crafted content into the CLI, after which embedded approval input can authorize shell commands without separate consent.

CVSS severity8.4
High
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authorization in Kiro CLI before 1.28.0 allows local users to execute arbitrary tools through content piped over standard input. The tool authorization prompt consumes bytes from the same redirected input stream as untrusted prompt content without validating their source. Exploitation requires a user to pipe attacker-crafted content into the CLI, after which embedded approval input can authorize shell commands without separate consent.

The record

CVE
CVE-2026-9255
Published
May 22, 2026
Updated
May 22, 2026
Vendor
Amazon Web Services
Product
Kiro CLI
Classifications
CWE-862, CAPEC-233, T1059
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 22, 2026CVE publishedPublication date reported by the CVE source.
  2. May 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.28.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Amazon Web Services · Kiro CLIversion=0 <1.28.0

Published CVSS scores

7.8Amazon Web ServicesCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.4Amazon Web ServicesCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-862Missing Authorization
CAPEC-233Privilege Escalation
T1059Command and Scripting Interpreter

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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