Is CVE-2026-103474 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-103474 being exploited in the wild.

How severe is CVE-2026-103474?

High severity, with a CVSS score of 8.8, published 30 September 2026.

Which products and versions are affected?

Yii-Starter-Kit Yii2-Starter-Kit through 4.2.0.

Is there a fix for CVE-2026-103474?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-103474 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-103474?

Check whether you run Yii-Starter-Kit Yii2-Starter-Kit at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-103474: yii2-starter-kit arbitrary code execution via unvalidated file upload

CVE-2026-103474 · Severity: high · CVSS 8.8 · Published 2026-09-30

yii2-starter-kit is a web application framework based on Yii2 used to build web applications. An authenticated manager can upload PHP files to the web-accessible storage directory by bypassing file type validation in the backend, allowing execution of arbitrary code on the server and full compromise of the application.

Technologies: Yii-Starter-Kit Yii2-Starter-Kit. Vendors: Yii-Starter-Kit.

Quick answers

Is CVE-2026-103474 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-103474 being exploited in the wild.
How severe is CVE-2026-103474?: High severity, with a CVSS score of 8.8, published 30 September 2026.
Which products and versions are affected?: Yii-Starter-Kit Yii2-Starter-Kit through 4.2.0.
Is there a fix for CVE-2026-103474?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-103474 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-103474?: Check whether you run Yii-Starter-Kit Yii2-Starter-Kit at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

yii2-starter-kit through 4.2.0 fails to validate file types in the backend storage upload actions (StorageController), allowing authenticated users with manager role to upload PHP scripts. The upload action does not filter file extensions or MIME types, enabling attackers to place executable code in a web-accessible directory and trigger code execution via direct HTTP requests to the uploaded files.

Affected products

yii-starter-kit yii2-starter-kit through 4.2.0

Timeline

2026-09-30: disclosed

References

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