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exceljs

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Excel Workbook Manager - Read and Write xlsx and csv Files.

Latest release4.4.0
Declared licenseMIT
Listed maintainersguyonroche, siemienik
Runtime dependencies9
Install-time scriptsNone declared
Integrity metadataRecorded by registry
Attestation metadataNot recorded
Registry deprecationNot marked deprecated
Direct dependencies of 4.4.0

Fetched 14/11/2026, 23:50:42 UTC · Original registry metadata

Release history

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Advisories & recorded fixes

medium6.3
CVE-2026-128336

ExcelJS through 4.4.0 Prototype Pollution via __proto__ Defined Name

ExcelJS through 4.4.0 contains a prototype pollution vulnerability that allows attackers to add numeric keys to Object.prototype through a crafted defined name referencing a proto sheet. Attackers can supply an xlsx whose xl/workbook.xml definedName range targets proto, causing CellMatrix to write empty arrays onto Object.prototype process-wide when workbook.xlsx.load() runs.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.3
CVE-2026-128337

ExcelJS through 4.4.0 Prototype Pollution via x14 Conditional Formatting Rule ID

ExcelJS through 4.4.0 contains a prototype pollution vulnerability in mergeConditionalFormattings that allows attackers to modify Object.prototype by supplying an x14:cfRule id of proto. Attackers can craft an xlsx file that, when loaded with xlsx.load(), sets properties such as type, direction, border and cfvo on every object in the process until it restarts.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.7
CVE-2026-128338

ExcelJS through 4.4.0 Memory Exhaustion via Unbounded Worksheet Column Range

exceljs through 4.4.0 contains a memory exhaustion vulnerability that allows attackers to crash applications by supplying a worksheet col element with an unbounded max attribute. Attackers can craft a small workbook with a huge max value, causing xlsx.load() to allocate hundreds of millions of Column objects and abort the process with an uncatchable heap out-of-memory error.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.7
CVE-2026-128339

ExcelJS through 4.4.0 Memory Exhaustion via Oversized Merged Cell Range

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.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.7
CVE-2026-128340

ExcelJS through 4.4.0 Memory Exhaustion via Oversized Defined Name Range

ExcelJS through 4.4.0 contains a memory exhaustion vulnerability that allows attackers to crash applications by supplying a workbook with an oversized defined-name range. DefinedNames.addEx expands ranges such as S!$A$1:$XFD$1048576 from xl/workbook.xml cell by cell, causing an uncatchable fatal heap out-of-memory error during xlsx.load().

No structured fix or guidance is available here. Check the latest publisher advisory.

Public exploit reference

exceljs · exceljs
high8.7
CVE-2026-128341

ExcelJS through 4.4.0 Denial of Service via Oversized Data Validation sqref

ExcelJS through 4.4.0 contains a resource exhaustion vulnerability in data-validations-xform.js that allows attackers to exhaust CPU and memory by supplying unbounded sqref ranges. Attackers can provide a small crafted workbook with a sqref of A1:XFD1048576 to make xlsx.load() iterate billions of addresses, blocking the event loop and crashing the process with an uncatchable out-of-memory error.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.7
CVE-2026-128342

ExcelJS through 4.4.0 Denial of Service via Oversized Worksheet sheetId

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.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.7
CVE-2026-128343

ExcelJS through 4.4.0 Denial of Service via Oversized Row Number

exceljs through 4.4.0 contains a denial of service vulnerability that allows attackers to block the event loop by supplying unbounded row r attributes parsed in row-xform.js. Attackers can craft an XLSX file with a row numbered far beyond Excel's limit, making getSheetValues(), workbook writes and CSV export consume time proportional to that number.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.7
CVE-2026-128344

ExcelJS through 4.4.0 Memory Exhaustion via Oversized Image Anchor Column

ExcelJS through 4.4.0 contains a memory exhaustion vulnerability that allows attackers to crash applications by supplying a workbook with an unbounded image anchor column in the drawing part. Attackers can set an anchor column such as 300000000 in xl/drawings/drawing1.xml so reading getImages() anchor positions makes Worksheet.getColumn allocate millions of Column objects and abort with a heap out-of-memory error.

No structured fix or guidance is available here. Check the latest publisher advisory.

Public exploit reference

exceljs · exceljs
medium6.9
CVE-2026-128345

ExcelJS through 4.4.0 ReDoS via slideFormula Shared Formula Translation

ExcelJS through 4.4.0 contains a regular expression denial of service vulnerability in slideFormula in lib/utils/shared-formula.js when translating shared formulas to child cells. Attackers can supply a crafted spreadsheet with very long master formulas, such as runs of hyphens, causing quadratic regex backtracking that blocks the Node.js event loop.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.7
CVE-2026-128346

ExcelJS through 4.4.0 Resource Exhaustion via Streaming WorkbookReader Temporary Files

ExcelJS through 4.4.0 contains a resource leak vulnerability in the streaming WorkbookReader.parse that leaves temporary files and open descriptors when sheet parsing fails or iteration stops early. Attackers can repeatedly upload malformed multi-sheet workbooks with worksheets placed before xl/sharedStrings.xml to fill the temporary directory and exhaust file descriptors.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.7
CVE-2026-128347

ExcelJS through 4.4.0 Arbitrary File Read via WorkbookWriter addImage Filename

ExcelJS through 4.4.0 contains an arbitrary file read vulnerability in the streaming WorkbookWriter that allows attackers to read local files by supplying crafted image filenames to addImage. Attackers can inject ../ path segments into user-controlled image paths, causing addMedia to embed any file readable by the Node.js process under xl/media in the generated workbook.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
medium4.2
CVE-2026-128348

ExcelJS through 4.4.0 Formula Injection via Table Totals Row Column Names

ExcelJS through 4.4.0 contains a formula injection vulnerability in the totals row formula getter in lib/doc/table.js that fails to escape [, ], # and ' characters in structured reference column names. Attackers can supply column names containing ] via untrusted input like imported CSV headers to inject formulas such as HYPERLINK that exfiltrate cell values when users open and click the generated workbook.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.4
CVE-2026-78209

exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values

exceljs through 4.4.0 fails to neutralize leading equals, plus, minus, or at signs in cell values written to CSV output. Attackers who can influence exported cell values can inject formulas that execute when the CSV file is opened in a spreadsheet application, potentially exfiltrating data or performing other malicious actions.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.7
CVE-2026-78208

exceljs through 4.4.0 Path Traversal via Unvalidated addImage filename

exceljs through 4.4.0 contains a path traversal vulnerability in the Workbook.addImage() function that fails to validate file paths. Attackers can supply arbitrary file paths to read any file accessible to the Node.js process and embed it in the generated workbook.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
critical9.4
CVE-2026-78207

exceljs through 4.4.0 Prototype Pollution via deepMerge Reached From Note Serialization

exceljs through 4.4.0 contains a prototype pollution vulnerability in the deepMerge helper that fails to reject proto, constructor, or prototype keys when merging note objects. Attackers can assign parsed JSON with a malicious proto property to cell notes, modifying Object.prototype and affecting all plain objects created in the process.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs
high8.7
CVE-2026-78206

exceljs through 4.4.0 Uncontrolled Resource Consumption via Unbounded xlsx Decompression

exceljs through 4.4.0 decompresses all entries from supplied xlsx archives into memory without limits on entry size, total size, or compression ratio. Attackers can upload highly compressed workbooks that expand to gigabytes in memory, exhausting available resources and causing denial of service.

No structured fix or guidance is available here. Check the latest publisher advisory.

Exploitation not established

exceljs · exceljs