CVE-2026-78209

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.

Scoring

Severity
HIGH
CVSS base score
8.4
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N
EPSS probability
0.29%
CWE
CWE-1236
Published
2026-08-24
Last modified
2026-08-29

Affected products

Weakness type

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