Vulnerability-Lookup

CVE-2026-78209 (GCVE-0-2026-78209)

Vulnerability from cvelistv5 – Published: 2026-08-24 00:30 – Updated: 2026-08-24 18:02

Title

exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values

Summary

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.

Severity

8.4 (High)


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

8.2 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-24 18:02 UTC

CWE

CWE-1236 - Improper Neutralization of Formula Elements in a CSV File

Assigner

VulnCheck mitre root

References

4 references

URL	Tags
https://github.com/exceljs/exceljs	product
https://github.com/mateocallec/exceljs-hardened/s…	third-party-advisory
https://github.com/exceljs/exceljs/blob/v4.4.0/li…	technical-description
https://www.vulncheck.com/advisories/exceljs-thro…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version	CPE status
exceljs	exceljs	Affected: 0 , ≤ 4.4.0 (semver) cpe:2.3:a:exceljs_project:exceljs::::::::

Date Public

2026-08-23 00:00

Credits

Matéo Florian Callec

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-78209

Vulnerability from fkie_nvd - Published: 2026-08-24 01:16 - Updated: 2026-08-24 18:17

Severity

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

Summary

References

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

Impacted products

	Vendor	Product	Version

JSON

To clipboard

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          "collectionURL": "https://www.npmjs.com/package/exceljs",
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  "lastModified": "2026-08-24T18:17:31.060",
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          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
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GHSA-4W2G-JRQM-G99Q

Vulnerability from github – Published: 2026-08-24 03:31 – Updated: 2026-08-24 03:31

Details

Severity

8.2 (High)


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

8.4 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-78209"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1236"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-24T01:16:58Z",
    "severity": "HIGH"
  },
  "details": "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.",
  "id": "GHSA-4w2g-jrqm-g99q",
  "modified": "2026-08-24T03:31:06Z",
  "published": "2026-08-24T03:31:06Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-9wxc-4rhw-hfrw"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-78209"
    },
    {
      "type": "WEB",
      "url": "https://github.com/exceljs/exceljs"
    },
    {
      "type": "WEB",
      "url": "https://github.com/exceljs/exceljs/blob/v4.4.0/lib/csv/csv.js#L109-L182"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/exceljs-through-csv-formula-injection-via-unescaped-cell-values"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-78209 (GCVE-0-2026-78209)

FKIE_CVE-2026-78209

GHSA-4W2G-JRQM-G99Q

Tags

Sightings

Nomenclature