CVE-2026-128346
Received Received - Intake

Resource Leak in ExcelJS WorkbookReader.parse

Publication date: 2026-11-13

Last updated on: 2026-11-13

Assigner: VulnCheck

Description
ExcelJS through 4.4.0 contains a resource leak vulnerability in the streaming WorkbookReader.parse that leaves temporary files and open descriptors when sheet parsing fails or iteration stops early. Attackers can repeatedly upload malformed multi-sheet workbooks with worksheets placed before xl/sharedStrings.xml to fill the temporary directory and exhaust file descriptors.

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Meta Information

Published
2026-11-13
Last Modified
2026-11-13
Generated
2026-11-13
AI Q&A
2026-11-13
EPSS Evaluated
N/A
NVD
CVE-2026-128346
EUVD
EUVD-2026-125153

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
exceljs exceljs From 0 (inc) to 4.4.0 (inc)

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-459 The product does not properly "clean up" and remove temporary or supporting resources after they have been used.

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Executive Summary

ExcelJS through version 4.4.0 has a resource leak vulnerability in the streaming WorkbookReader.parse function. When sheet parsing fails or iteration stops early, temporary files and open file descriptors are not properly released. Attackers can exploit this by uploading malformed multi-sheet workbooks with worksheets placed before xl/sharedStrings.xml to fill the temporary directory and exhaust file descriptors.

Detection Guidance

Monitor temporary directories for unexpected file accumulation, especially files related to ExcelJS parsing. Check for processes holding excessive file descriptors using commands like 'lsof' or 'ss -s'. Look for repeated failures in Excel file parsing logs.

Impact Analysis

This vulnerability can lead to denial of service by exhausting system resources. Temporary files and file descriptors accumulate over time, eventually preventing the process from opening new files or sockets. Attackers can repeatedly upload malformed Excel files to trigger this issue.

Mitigation Strategies

Upgrade ExcelJS to version 4.4.1 or later. Implement strict input validation for uploaded Excel files. Monitor and limit temporary directory usage. Restart services periodically to clear accumulated resources.

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