CVE-2026-78209

HIGH 8.2

exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values

CVSS Score

8.2

EPSS Score

0.0%

EPSS Percentile

0th

exceljs-hardened versions before 5.0.0 fail to neutralize leading equals, plus, minus, or at signs in cell values written to CSV output. Attackers who can influence exported cell values can inject formulas that execute when the CSV file is opened in a spreadsheet application, potentially exfiltrating data or performing other malicious actions.

CWE	CWE-1236
Vendor	exceljs
Product	exceljs
Published	Aug 24, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

High

Integrity

Low

Availability

None

Affected Versions

exceljs / exceljs

0 ≤ 4.4.0

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/exceljs/exceljs github.com: https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-9wxc-4rhw-hfrw github.com: https://github.com/exceljs/exceljs/blob/v4.4.0/lib/csv/csv.js#L109-L182 vulncheck.com: https://www.vulncheck.com/advisories/exceljs-through-csv-formula-injection-via-unescaped-cell-values

Credits

Matéo Florian Callec