Dashboard / CVE-2026-78207

CVE-2026-78207

CRITICAL
INFO Priority: 0.06 BB Relevance: 79/100
Published: 2026-08-24 Modified: 2026-11-08 First seen: 2026-11-08 Status: active

Attack Surface

Network Low Complexity No Auth No Interaction Conf. Impact Integ. Impact

CVSS Vector Breakdown

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

Description

exceljs through 4.4.0 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.

Weakness Classification (1)

Affected Software (1)

VendorProductVersion
exceljs exceljs 0

References & Advisories (4)

Bug Bounty Relevance

79 / 100
✓ Network accessible
✓ No authentication
✓ Low complexity
✓ No user interaction

CVSS Score

9.3 / 10.0 v4.0
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

EPSS — Exploitation Probability

0.60%
Raw Score 0.006030
Percentile 49.4%
Date 2026-11-13

EPSS Trend

2026-11-13
0.00603
2026-11-12
0.00603
2026-11-10
0.00603
2026-11-09
0.00603
2026-11-08
0.00603

Intelligence Sources

mitre ref →

External Links