CVE-2023-30533
📋 TL;DR
CVE-2023-30533 is a prototype pollution vulnerability in SheetJS Community Edition that allows attackers to modify JavaScript object prototypes by uploading a specially crafted file. This affects applications using SheetJS to parse Excel files, potentially leading to denial of service, data corruption, or remote code execution. All users of SheetJS Community Edition versions before 0.19.3 are affected.
💻 Affected Systems
- SheetJS Community Edition (sheetjs)
📦 What is this software?
Sheetjs by Sheetjs
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment.
Likely Case
Denial of service, application crashes, or data corruption in affected applications.
If Mitigated
Limited impact with proper input validation and file upload restrictions in place.
🎯 Exploit Status
Exploitation requires uploading a malicious file to an application using vulnerable SheetJS versions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.19.3 and later
Vendor Advisory: https://cdn.sheetjs.com/advisories/CVE-2023-30533
Restart Required: No
Instructions:
1. Update SheetJS Community Edition to version 0.19.3 or later using npm update sheetjs. 2. Verify the update with npm list sheetjs. 3. Test file parsing functionality after update.
🔧 Temporary Workarounds
Input Validation and File Restrictions
allImplement strict file type validation and size limits for uploaded files.
Sandbox File Processing
allProcess uploaded files in isolated containers or serverless functions.
🧯 If You Can't Patch
- Disable file upload functionality for untrusted users
- Implement Web Application Firewall (WAF) rules to block malicious file uploads
🔍 How to Verify
Check if Vulnerable:
Check package.json or run npm list sheetjs to see if version is below 0.19.3.Check Version:
npm list sheetjs | grep sheetjsVerify Fix Applied:
Confirm sheetjs version is 0.19.3 or higher using npm list sheetjs.📡 Detection & Monitoring
Log Indicators:
- Unusual file upload patterns
- Application crashes during file parsing
- Error logs mentioning SheetJS or prototype pollution
Network Indicators:
- Large or unusual file uploads to endpoints handling Excel files
- Multiple failed parsing attempts
SIEM Query:
source="application.log" AND ("sheetjs" OR "prototype pollution" OR "file parsing error")🔗 References
- https://cdn.sheetjs.com/advisories/CVE-2023-30533
- https://git.sheetjs.com/sheetjs/sheetjs/issues/2986
- https://git.sheetjs.com/sheetjs/sheetjs/src/branch/master/CHANGELOG.md
- https://cdn.sheetjs.com/advisories/CVE-2023-30533
- https://git.sheetjs.com/sheetjs/sheetjs/issues/2986
- https://git.sheetjs.com/sheetjs/sheetjs/src/branch/master/CHANGELOG.md
