Dashboard / CVE-2026-128336

CVE-2026-128336

MEDIUM
MEDIUM Priority: 0.03 BB Relevance: 63/100
Published: 2026-11-13 Modified: 2026-11-13 First seen: 2026-11-13 Status: active

Attack Surface

Network No Auth No Interaction

CVSS Vector Breakdown

AV: Network
AC: High
PR: None
UI: None
AT: Present
VC: None
VI: Low
VA: Low

Description

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.

Weakness Classification (1)

Affected Software (2)

VendorProductVersion
exceljs exceljs 0
exceljs exceljs 0

References & Advisories (5)

Bug Bounty Relevance

63 / 100
✓ Network accessible
✓ No authentication
✓ No user interaction

CVSS Score

6.3 / 10.0 v4.0
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

EPSS — Exploitation Probability

0.43%
Raw Score 0.004250
Percentile 37.3%
Date 2026-11-13

Intelligence Sources

mitre ref →
nvd ref →

External Links