CVE-2025-48985
📋 TL;DR
This vulnerability in Vercel's AI SDK allows users to bypass filetype whitelists when uploading files, potentially enabling malicious file uploads. It affects all users of vulnerable versions of the AI SDK. The issue has been fixed in patched versions.
💻 Affected Systems
- Vercel AI SDK
⚠️ Risk & Real-World Impact
Worst Case
Attackers could upload malicious files (e.g., scripts, malware) that bypass security controls, potentially leading to remote code execution or data compromise.
Likely Case
Unauthorized file uploads that bypass intended restrictions, potentially enabling file-based attacks or data exfiltration.
If Mitigated
With proper input validation and file handling controls, impact is limited to potential file storage issues.
🎯 Exploit Status
Exploitation requires user interaction to upload files, but bypass technique is straightforward once discovered.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 5.0.52, 5.1.0-beta.9, or 6.0.0-beta
Vendor Advisory: https://vercel.com/changelog/cve-2025-48985-input-validation-bypass-on-ai-sdk
Restart Required: No
Instructions:
1. Update package.json to use patched version. 2. Run npm update @ai-sdk/react or equivalent for your framework. 3. Test file upload functionality.
🔧 Temporary Workarounds
Implement server-side file validation
allAdd additional file validation on the server side before processing uploaded files
Restrict file upload endpoints
allLimit access to file upload endpoints through authentication and authorization controls
🧯 If You Can't Patch
- Implement strict server-side file type validation independent of SDK
- Monitor file upload endpoints for suspicious activity and implement rate limiting
🔍 How to Verify
Check if Vulnerable:
Check package.json for @ai-sdk/react version. If version is below 5.0.52, 5.1.0-beta.9, or 6.0.0-beta, you are vulnerable.Check Version:
npm list @ai-sdk/reactVerify Fix Applied:
Verify the installed version is 5.0.52 or higher, or the beta versions specified. Test file upload with various file types to ensure whitelist enforcement works.📡 Detection & Monitoring
Log Indicators:
- Unexpected file types being uploaded
- File upload attempts with unusual extensions or MIME types
- Failed file validation events
Network Indicators:
- HTTP POST requests to file upload endpoints with unusual content-types
- Large number of file upload attempts
SIEM Query:
source="web_server" AND (url_path="*/upload*" OR url_path="*/file*") AND (http_method="POST" OR http_method="PUT") AND NOT content_type IN ["image/jpeg", "image/png", "application/pdf"]