CVE-2026-78209 [HIGH] – exceljs through 4.4.0 fails to neutralize leading equals, plus, minus, or at signs in cell

exceljs through 4.4.0 fails 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.