---
title: "CVE-2026-103474: yii2-starter-kit - Unrestricted File Upload"
description: "yii2-starter-kit <= 4.2.0 contains an unrestricted file upload caused by failure to validate file types in backend storage upload actions, letting authenticated managers upload and execute arbitrary PHP code, exploit requires manager role."
url: https://panop.io/threat-heartbeat/CVE-2026-103474/
---

# CVE-2026-103474 yii2-starter-kit - Unrestricted File Upload

yii2-starter-kit <= 4.2.0 contains an unrestricted file upload caused by failure to validate file types in backend storage upload actions, letting authenticated managers upload and execute arbitrary PHP code, exploit requires manager role.

CVSS base score 8.8 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.39% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-103474)

## Details

Type

Unrestricted File Upload

Impact

Remote Code Execution

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Published

30 September 2026

Updated

15 October 2026

Weakness

[CWE-434](https://cwe.mitre.org/data/definitions/434.html)

## Vendor fix

Update to a version later than 4.2.0 or apply patches that validate file types properly.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-103474](https://nvd.nist.gov/vuln/detail/CVE-2026-103474)
- [https://github.com/yii-starter-kit/yii2-starter-kit](https://github.com/yii-starter-kit/yii2-starter-kit)
- [https://github.com/yii-starter-kit/yii2-starter-kit/blob/cc2c451e8c959c7300b04efea597706a38609f58/backend/modules/file/controllers/StorageController.php#L36](https://github.com/yii-starter-kit/yii2-starter-kit/blob/cc2c451e8c959c7300b04efea597706a38609f58/backend/modules/file/controllers/StorageController.php#L36)
- [https://github.com/yii-starter-kit/yii2-starter-kit/issues/797](https://github.com/yii-starter-kit/yii2-starter-kit/issues/797)
- [https://www.vulncheck.com/advisories/yii2-starter-kit-through-4.2.0-unrestricted-file-upload-rce](https://www.vulncheck.com/advisories/yii2-starter-kit-through-4.2.0-unrestricted-file-upload-rce)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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