CVE-2026-78207

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...

CVE-2026-78207

exceljs-hardened before 5.0.0 (also tracked as exceljs through 4.4.0) contains a prototype pollution vulnerability in the deepMerge helper. The helper fails to reject __proto__, constructor, or prototype keys when merging note objects, allowing an attacker to assign parsed JSON with a malicious _...

EUVD-2026-64682

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...

PT-2026-79800

Name of the Vulnerable Software and Affected Versions exceljs-hardened versions prior to 5.0.0 Description An issue exists in the deepMerge helper that fails to reject proto , constructor, or prototype keys when merging note objects. This allows attackers to assign parsed JSON containing a...