Auth bypass in Yii2-Starter-Kit
CVE-2026-103476
yii2-starter-kit through 4.2.0 fails to validate article publication status in the attachment-download endpoint, allowing unauthenticated attackers to download files from draft articles. Attackers can enumerate sequential attachment identifiers to retrieve files from unpublished articles without authentication or authorization checks.
Vulnerability class: IDOR (Insecure Direct Object Reference)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/yii-starter-kit/yii2-starter-kit/issues/797 (issue-tracking)
- github.com/yii-starter-kit/yii2-starter-kit (product)
- github.com/yii-starter-kit/yii2-starter-kit/blob/cc2c451e8c959c7300b04efea59770… (technical-description)
- www.vulncheck.com/advisories/yii2-starter-kit-through-4.2.0-unauthorized-file-d… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-103476?
- CVE-2026-103476 is a medium-severity vulnerability in Yii2-Starter-Kit, classified under Authorization Bypass Through User-Controlled Key. CVSS score: 5.3/10. Published 2026-09-30.
- How severe is CVE-2026-103476?
- Medium severity. CVSS v3 base score is 5.3 out of 10.