CVE-2026-128342

ExcelJS through 4.4.0 Denial of Service via Oversized Worksheet sheetId

Published Nov 13, 2026 CVSS 4.0 · 8.7 High EPSS n/a KEV · Not listed

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.

Affected Products

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

unaffected

Version	Status	Constraints
`0`	affected	≤ 4.4.0

No data.

No data available yet.

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

No advisories available

Metrics

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.

References

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

History

Nov 13, 2026 9:45 AM Description updated. Title updated. First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated. Added references. Scoring metrics updated View changes

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