CVE-2026-78209

HIGHPre-NVD 8.28.2—
EchelonGraph scoreHIGH confidence

Score 8.2 from GitHub Security Advisory (severity: HIGH) published 2026-08-24. a secondary CVSS source baseline 8.2; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
8.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.2Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
8.2
EG Score
8.2(high)
EG Risk
37(Track)
EG Risk 37/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity82% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
22%
KEV
Not listed

Published

August 24, 2026

Last Modified

August 24, 2026

Advisory Details (4)

Auto-updated Aug 24, 2026
Patch available. Sources: github.
generic

exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values | Advisories | VulnCheck

https://www.vulncheck.com/advisories/exceljs-through-csv-formula-injection-via-unescaped-cell-values
generic

exceljs/lib/csv/csv.js at v4.4.0 · exceljs/exceljs · GitHub

https://github.com/exceljs/exceljs/blob/v4.4.0/lib/csv/csv.js#L109-L182
github Patch Available

CSV Formula Injection in exceljs via `CSV.write()` · Advisory · mateocallec/exceljs-hardened · GitHub

https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-9wxc-4rhw-hfrw
generic

GitHub - exceljs/exceljs: Excel Workbook Manager · GitHub

https://github.com/exceljs/exceljs

Vendor Advisories for CVE-2026-78209(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 15× in last 7d / 15× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-08-26 04:13 UTCGHSA enrichment
  2. 2026-08-25 16:58 UTCEG score recompute
  3. 2026-08-25 16:57 UTCGHSA enrichment
  4. 2026-08-25 13:49 UTCEPSS rescore
  5. 2026-08-25 05:36 UTCGHSA enrichment
  6. 2026-08-24 18:24 UTCEG score recompute
  7. 2026-08-24 18:23 UTCGHSA enrichment
  8. 2026-08-24 18:16 UTCEG score recompute
  9. 2026-08-24 18:16 UTCGHSA enrichment
  10. 2026-08-24 14:18 UTCEPSS rescore
  11. 2026-08-24 12:51 UTCEG score recompute
  12. 2026-08-24 12:51 UTCGHSA enrichment
  13. 2026-08-24 01:38 UTCEG score recompute
  14. 2026-08-24 00:36 UTCEG score recompute
  15. 2026-08-24 00:35 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-78209?
CVE-2026-78209 is a high vulnerability published on August 24, 2026. 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…
When was CVE-2026-78209 disclosed?
CVE-2026-78209 was first published in the National Vulnerability Database on August 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-78209 actively exploited?
CVE-2026-78209 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 78.5% of all scored CVEs.
What is the CVSS score of CVE-2026-78209?
CVE-2026-78209 has a CVSS v3 base score of 8.2 (NVD).
How do I remediate CVE-2026-78209?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-78209, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-78209

Explore →

Is Your Infrastructure Affected by CVE-2026-78209?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs