P4Verified

CVE-2026-78207: exceljs 0 through 4.4.0

CVE-2026-78207. CVSS 3.1 base score 9.4 (CRITICAL, Vendor/CNA). EPSS 0.00603 (percentile 0.4743), scored 13-Oct-2026.

Affected technology

exceljs · 0 through 4.4.0
exceljs

Description’s affected range: through 4.4.0

Component: Not specified by the source

Attack conditions (Vendor/CNA, CVSS 4.0): Network (remote) · No privileges required · No user interaction required

What an attacker can do

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. Vendor/CNA’s CVSS 4.0 assessment (base score 9.3/10) rates confidentiality and integrity impact as high; availability impact as low.

Published 14-Oct-2026 15:58 UTC

CWE: CWE-1321
CCR priority: 37.8 /100 (P4)
CVSS 3.1: 9.4 /10 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L · Vendor/CNA
EPSS: 0.00603 · percentile 0.4743 · 2026-10-13
KEV: no

Provenance

NVD CVE API 2.0 · Source record · observed 2026-10-14 15:56:36.793806+00:00 UTC

Stable permalink: https://cybercodered.org/item/cve-cve-2026-78207.html