GHSA-fr76-5637-w3g9 Sharp has Unrestricted File Upload via Client-Controlled Validation Rules

• Packagist code16/sharp: < 9.20.0 → fixed in 9.20.0

Summary The `code16/sharp` Laravel admin panel package contains a vulnerability in its file upload endpoint that allows authenticated users to bypass all file type restrictions. Details 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. The vulnerable code is located in `src/Http/Controllers/Api/ApiFormUploadController.php` at line 24. Impact This vulnerability leads to several critical security risks: Attackers can upload arbitrary files, including PHP webshells, to the server. For more details on the package, visit: https://github.com/code16/sharp MIME type and extension validation can be bypassed entirely via client-controlled rules. Review the CWE definition here: https://cwe.mitre.org/data/definitions/434.html If the storage disk is configured to be publicly accessible, this can lead to Remote Code Execution (RCE). See the vendor repository: https://github.com/code16/sharp (Note: Under default configurations, executing uploaded PHP files directly is not possible unless a public disk configuration is in place.) Patches This issue has been addressed by removing the client-controlled validation rules and strictly defining upload rules server-side. The fix is available in pull request https://github.com/code16/sharp/pull/714. Workarounds • Restrict Disk Access: 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. For more details on Laravel disk configurations, visit: https://laravel.com/docs/13.x/filesystem Credits Reported by zaurgsynv.