CVE-2026-128342 ExcelJS through 4.4.0 Denial of Service via Oversized Worksheet sheetId

8.7 highEPSS 0.6%

High (8.7) in exceljs exceljs. EPSS 0.6% estimated probability of exploitation activity in the next 30 days.

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Affected
Versions
References
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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.

Severity

CVSS 4.0

8.7 high

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

CVSS 3.1

7.5 high

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

EPSS: 0.6% estimated probability of exploitation activity in the next 30 days; 51st percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
CWE: CWE-606 Unchecked Input for Loop Condition
Published: 2026-11-13 10:18 UTC
Modified: 2026-11-13 15:48 UTC
Assigned by: VulnCheck (CNA)
NVD analysis: Awaiting analysis
Record from: the NVD, synced 2026-11-13 16:08 UTC

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Affected

exceljs:exceljs

Versions

From the CNA's record in the CVE List.

Product	Affected
exceljs	through 4.4.0

References

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