CVE-2026-78207
CRITICAL
9,3
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: none
User Interaction: none
Confidentiality: N/A
Integrity: N/A
Availability: N/A
CRITICAL
9,4
Source: [email protected]
Attack Vector: network
Attack Complexity: low
Privileges Required: none
User Interaction: none
Scope: unchanged
Confidentiality: high
Integrity: high
Availability: low
Description
AI Translation Available
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.
1321
Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
IncompleteCommon Consequences
Security Scopes Affected:
Confidentiality
Integrity
Availability
Potential Impacts:
Read Application Data
Modify Application Data
Dos: Crash, Exit, Or Restart
Applicable Platforms
Languages:
JavaScript
https://github.com/exceljs/exceljs
https://github.com/exceljs/exceljs/blob/v4.4.0/lib/utils/under-dash.js#L155-L181
https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-qwr4-7…
https://www.vulncheck.com/advisories/exceljs-through-prototype-pollution-via-de…