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Vulnerabilities

Vulnerability · 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.

Published Aug 24, 2026 · catalog updated Oct 14, 2026 · exceljs through 4.4.0 fails

Check if you run it

No confirmed exploitation is on record for CVE-2026-78209. EPSS is 0.41%. Act only if a listed version of exceljs through 4.4.0 fails is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (exceljs through 4.4.0 fails).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.4
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.41%
Remediation
Advisory link
Affected products
See sources for product scope

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.

No affected version ranges are stored yet. Use the vendor advisory before you decide this record does not apply.

How to fix CVE-2026-78209

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-78209. EPSS is 0.41%. Act only if a listed version of exceljs through 4.4.0 fails is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-1236: Improper Neutralization of Formula Elements in a CSV File. EPSS 0.41%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Aug 24, 2026 · NIST NVD

    Detected

    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.

  2. Oct 14, 2026 · NIST NVD

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2026-78209

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-78209

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-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 exfiltr

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.