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

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HIGH

Tool Execution Without Authorization via Piped Stdin in Kiro CLI

Published May 22, 2026

8.4

HIGH

CVSS 4.0

EPSS 0.18%

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.

Affected products

Vendor AWS Product Kiro CLI Default
unaffected
- Version
  0
  Status
  affected
  Constraints
  <1.28.0

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor

Product

Default status

Versions

AWS

Kiro CLI

unaffected

Version	Status	Constraints
0	affected	<1.28.0

Remediation

No remediation recorded yet.

Metrics

0.18% 0.00175

Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 4, 2026.

EPSS probability 0.00175

Score over time

May-Oct 2026

EPSS v4
EPSS v5

Percentile over time

EPSS v4
EPSS v5

Table of values (3 key points)

Flat stretches are collapsed. Showing up to 120 newest points.

Date	Score	Percentile	Model
Oct 4, 2026	0.18% (0.00175)	6.36th	v5 (v2026.06.15)
Jun 15, 2026	0.15% (0.00152)	4.72th	v5 (v2026.06.15)
May 23, 2026	0.01% (0.00013)	2.09th	v4 (v2025.03.14)

Weaknesses (1)

CWE-862

Missing Authorization

References (2)

https://aws.amazon.com/security/security-bulletins/2026-035-aws/
vendor-advisoryVendor Advisory
https://kiro.dev/changelog/cli/1-28/
release-notesRelease Notes

Link	Providers	Tags
https://aws.amazon.com/security/security-bulletins/2026-035-aws/		vendor-advisoryVendor Advisory
https://kiro.dev/changelog/cli/1-28/		release-notesRelease Notes