CVE-2026-128339

ExcelJS through 4.4.0 Memory Exhaustion via Oversized Merged Cell Range

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

Description

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.

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

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 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.
Title		ExcelJS through 4.4.0 Memory Exhaustion via Oversized Merged Cell Range
First Time appeared		Exceljs Project Exceljs Project exceljs
Weaknesses		CWE-770
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/worksheet.js#L613-L632 https://github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/worksheet.js#L895-L901 https://github.com/exceljs/exceljs/issues/3107 https://github.com/exceljs/exceljs/pull/3114 https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-wh3v-83h4-rwwq https://www.vulncheck.com/advisories/exceljs-through-4.4.0-memory-exhaustion-via-oversized-merged-cell-range
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'}`