What is CVE-2026-9255?

CVE-2026-9255 is a high-severity vulnerability in Amazon Kiro Cli, classified under Missing Authorization. CVSS score: 7.8/10. Published 2026-05-22.

How severe is CVE-2026-9255?

High severity. CVSS v3 base score is 7.8 out of 10.

Auth bypass in Amazon Kiro Cli

CVE-2026-9255

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.

Vulnerability class: Broken Access Control

Published 2026-05-22 · last modified 2026-07-23.

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.001 (2.5th percentile), scored 2026-11-09.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 2nd percentile — 2.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.001 · change: -0.000

Affected products

Amazon Kiro Cli
AWS Kiro Cli — versions 0

Weakness classification (CWE)

CWE-862 — Missing Authorization

References

ff89ba41-3aa1-4d27-914a-91399e9639e5 (release-notes, Release Notes)
ff89ba41-3aa1-4d27-914a-91399e9639e5 (vendor-advisory, Vendor Advisory)

Frequently asked questions

What is CVE-2026-9255?: CVE-2026-9255 is a high-severity vulnerability in Amazon Kiro Cli, classified under Missing Authorization. CVSS score: 7.8/10. Published 2026-05-22.
How severe is CVE-2026-9255?: High severity. CVSS v3 base score is 7.8 out of 10.