Dashboard / CVE-2026-128337

CVE-2026-128337

HIGH
MEDIUM Priority: 0.04 BB Relevance: 67/100
Published: 2026-11-13 Modified: 2026-11-13 First seen: 2026-11-13 Status: active

Attack Surface

Network No Auth No Interaction Integ. Impact

CVSS Vector Breakdown

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

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.

Weakness Classification (1)

Affected Software (1)

VendorProductVersion
exceljs exceljs 0

References & Advisories (5)

Bug Bounty Relevance

67 / 100
✓ Network accessible
✓ No authentication
✓ No user interaction

CVSS Score

8.3 / 10.0 v4.0
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS — Exploitation Probability

0.45%
Raw Score 0.004450
Percentile 39.2%
Date 2026-11-13

Intelligence Sources

mitre ref →
nvd ref →

External Links