ShellCodeX vulnerability brief
CRITICAL
Received
CVE-2026-78207
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.
Published 24 Aug 2026, 01:16 UTC
Last modified 24 Aug 2026, 01:16 UTC
01
Attack profile
The conditions required to exploit this vulnerability and its potential impact.
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Not assessed
Confidentiality
Not assessed
Integrity
Not assessed
Availability
Not assessed
02
Affected products
Product applicability statements supplied with the NVD record.
NVD has not published structured affected-product data for this record.
03
Weakness classification
CWE categories help security teams group the underlying software weakness.
04
Source references
External advisories, patches and technical reports attached to this CVE record.