exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values (CVE-2026-78209) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-78209

exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values

Answer in brief

CVE-2026-78209 records a Unknown severity vulnerability in exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values. The current sources do not mark it as known exploited. The current feed maps exceljs/exceljs (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 24, 2026Updated Aug 24, 2026Source checked Aug 24, 2026First seen by HOL Aug 24, 2026Material review Aug 24, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Not reported

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps exceljs/exceljs (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
exceljs/exceljsgeneric	0	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for exceljs/exceljs.
Review the reported fix. Monitor this advisory for an available fix and review any installs of the affected package.

Evidence timeline and material changes

Published upstream
Aug 24, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 24, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 24, 2026

Sources and claim methodology

Upstream source description

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.

Quoted source text, attributed separately from HOL analysis.