ExcelJS Denial of Service via Unbounded Row Attributes

Executive Summary

This vulnerability is a denial of service issue in the exceljs library up to version 4.4.0. Attackers can exploit it by creating an XLSX file with an extremely high row number, far beyond Excel's normal limits. When the library processes this file, it attempts to handle the row count, causing event loop blocking and excessive resource consumption during operations like getSheetValues(), workbook writes, and CSV exports.

Useful 0 Not Useful 0

Detection Guidance

This vulnerability can be detected by monitoring for unusually large row numbers in XLSX files processed by exceljs. Check logs for getSheetValues(), workbook writes, or CSV export operations that take excessive time. No specific commands are provided in the context.

Useful 0 Not Useful 0

Impact Analysis

If you use the vulnerable exceljs library, an attacker could craft a malicious XLSX file that freezes or slows down your application by consuming excessive CPU and memory. This could disrupt normal operations, delay processing, or crash systems relying on the library for spreadsheet handling.

Useful 0 Not Useful 0

Mitigation Strategies

Upgrade exceljs to a version beyond 4.4.0 to address the DoS vulnerability. Implement input validation to reject XLSX files with row numbers exceeding Excel's limits. Monitor system performance for abnormal delays during file processing.

Useful 0 Not Useful 0