EUVD-2026-64682

exceljs-hardened before 5.0.0 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...

EUVD-2026-64683

exceljs-hardened before 5.0.0 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...

EUVD-2026-64684

exceljs-hardened versions before 5.0.0 fail 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...

EUVD-2026-64681

exceljs-hardened before 5.0.0 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...