Vulnerability · Published Aug 24, 2026 · Assigned by VulnCheck
CVE-2026-78209exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values
High 8.2
In plain English
A high-severity security flaw in exceljs from exceljs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities).
Severity (CVSS 3.1)8.2High
Exploit odds (30 days)0.4%top 64.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
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.
Affected products (as reported)
Weakness: CWE-1236 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N
References
- https://github.com/exceljs/exceljs product
- GitHub Security Advisory (GHSA-9wxc-4rhw-hfrw) third-party-advisory
- https://github.com/exceljs/exceljs/blob/v4.4.0/lib/csv/csv.js#L109-L182 technical-description
- VulnCheck Advisory: exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values third-party-advisory