CVE-2026-128339

HIGH 7.5

ExcelJS through 4.4.0 Memory Exhaustion via Oversized Merged Cell Range

CVSS Score

7.5

EPSS Score

0.0%

EPSS Percentile

0th

ExcelJS through 4.4.0 contains a memory exhaustion vulnerability in Worksheet._parseMergeCells that allows attackers to crash applications by supplying unbounded mergeCell ranges. Attackers can craft a small workbook with a mergeCell ref like A1:XFD1048576, causing xlsx.load() to create billions of Row and Cell objects and abort the process.

CWE	CWE-770
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-wh3v-83h4-rwwq github.com: https://github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/worksheet.js#L613-L632 github.com: https://github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/worksheet.js#L895-L901 github.com: https://github.com/exceljs/exceljs/issues/3107 github.com: https://github.com/exceljs/exceljs/pull/3114 vulncheck.com: https://www.vulncheck.com/advisories/exceljs-through-4.4.0-memory-exhaustion-via-oversized-merged-cell-range

Credits

Matéo Florian Callec