CVE-2026-128342

HIGH 7.5

ExcelJS through 4.4.0 Denial of Service via Oversized Worksheet sheetId

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

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.

CWE	CWE-606
Vendor	exceljs
Product	exceljs
Published	Nov 13, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Affected Versions

exceljs / exceljs

0 ≤ 4.4.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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

Credits

Matéo Florian Callec