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Advisories

exceljs through 4.4.0 Prototype Pollution via deepMerge Reached From Note Serialization

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severity
critical
date
Affecting

  • exceljs <= 4.4.0

CWE
  • CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
CVSS
9.3
CVSS V4 Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:L/SC:N/SI:N/SA:N
Credit
Matéo Florian Callec
Description
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 affecting all plain objects created in the process.

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