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Advisories

ExcelJS through 4.4.0 Prototype Pollution via x14 Conditional Formatting Rule ID

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Severity
high
Date
Affecting

  • exceljs <= 4.4.0

CWE
  • CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
CVSS
8.3
CVSS V4 Vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N
Credit
Matéo Florian Callec
Description
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.

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