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.
Metrics
Affected Vendors & Products
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Fri, 13 Nov 2026 09:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | ExcelJS through 4.4.0 Prototype Pollution via x14 Conditional Formatting Rule ID | |
| First Time appeared |
Exceljs Project
Exceljs Project exceljs |
|
| Weaknesses | CWE-1321 | |
| CPEs | cpe:2.3:a:exceljs_project:exceljs:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Exceljs Project
Exceljs Project exceljs |
|
| References |
|
|
| Metrics |
cvssV3_1
|
Projects
Sign in to view the affected projects.
MITRE
Status: PUBLISHED
Assigner: VulnCheck
Published:
Updated: 2026-11-13T09:33:37.679Z
Reserved: 2026-11-13T01:20:39.850Z
Link: CVE-2026-128337
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses