ExcelJS through 4.4.0 contains a denial of service vulnerability that allows attackers to block the event loop by supplying an unbounded sheetId in xl/workbook.xml. Attackers can provide a workbook with a huge sheetId, making the sparse worksheet array walk stall worksheets, getWorksheet and writeBuffer for seconds.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
exceljs exceljs unaffected
Version Status Constraints
0 affected ≤ 4.4.0

No data.

No data.

No data.

Project Subscriptions

Vendors Products
Exceljs Project Subscribe
Exceljs Subscribe
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/exceljs/exceljs cve-icon cve-icon
https://github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/workbook.js#L119-L125 cve-icon cve-icon
https://github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/workbook.js#L200-L206 cve-icon cve-icon
https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-9vv6-5g3h-prg5 cve-icon cve-icon
https://www.vulncheck.com/advisories/exceljs-through-4.4.0-denial-of-service-via-oversized-worksheet-sheetid cve-icon cve-icon
History

Fri, 13 Nov 2026 09:45:00 +0000

Type Values Removed Values Added
Description ExcelJS through 4.4.0 contains a denial of service vulnerability that allows attackers to block the event loop by supplying an unbounded sheetId in xl/workbook.xml. Attackers can provide a workbook with a huge sheetId, making the sparse worksheet array walk stall worksheets, getWorksheet and writeBuffer for seconds.
Title ExcelJS through 4.4.0 Denial of Service via Oversized Worksheet sheetId
First Time appeared Exceljs Project
Exceljs Project exceljs
Weaknesses CWE-606
CPEs cpe:2.3:a:exceljs_project:exceljs:*:*:*:*:*:*:*:*
Vendors & Products Exceljs Project
Exceljs Project exceljs
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-11-13T09:33:34.387Z

Reserved: 2026-11-13T01:20:41.765Z

Link: CVE-2026-128342

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-13T10:18:14.670

Modified: 2026-11-13T10:18:14.670

Link: CVE-2026-128342

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses