CVE-2026-33687 Sharp has Unrestricted File Upload via Client-Controlled Validation Rules
Authenticated users can bypass file type restrictions in Sharp by manipulating client-side validation rules, potentially leading to remote code execution if public storage is configured.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33687?
CVE-2026-33687 is a high-severity vulnerability in code16 sharp, published on 26 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-434
Which versions are affected by CVE-2026-33687?
2 open source packages ship an affected version, including code16/sharp. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
code16/sharp Packagist | All versions | 9.20.0 |
code16/sharp Packagist | All versions | 9.20.0 |
Products include Code16 Sharp.
How do I fix CVE-2026-33687?
Upgrade code16/sharp to 9.20.0 or later.
Is CVE-2026-33687 being exploited?
There is no known exploitation of CVE-2026-33687 in the wild and no public exploit code.
Other vulnerabilities in code16 sharp
Sources
Also known as GHSA-fr76-5637-w3g9.