CVE-2026-78209

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.

CVSS 4.0

8.4CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N

CVSS 3.1

8.2CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

EPSS

0.4% chance of exploitation in the next 30 days; higher than 34% of CVEs (scores of 2026-10-25)

CWE

CWE-1236

Published

2026-08-24

Modified

2026-10-14

Record from

the NVD, synced 2026-10-19

References

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

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