CVE-2026-78209
exceljs through 4.4.0 CSV Formula Injection via Unescaped Cell Values
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.
INFO
Published Date :
Aug. 24, 2026, 1:16 a.m.
Last Modified :
Aug. 31, 2026, 8:52 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 4.0 | HIGH | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update exceljs-hardened to version 5.0.0 or later.
- Sanitize cell values before writing to CSV.
- Implement input validation for cell data.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-78209.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-78209 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-78209
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-78209 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-78209 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
Aug. 29, 2026
Action Type Old Value New Value Changed 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. 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. Added Reference https://github.com/exceljs/exceljs Added Reference https://github.com/exceljs/exceljs/blob/v4.4.0/lib/csv/csv.js#L109-L182 Added Reference https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-9wxc-4rhw-hfrw Added Reference https://www.vulncheck.com/advisories/exceljs-through-csv-formula-injection-via-unescaped-cell-values Removed Reference https://github.com/exceljs/exceljs Removed Reference https://github.com/exceljs/exceljs/blob/v4.4.0/lib/csv/csv.js#L109-L182 Removed Reference https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-9wxc-4rhw-hfrw Removed Reference https://www.vulncheck.com/advisories/exceljs-through-csv-formula-injection-via-unescaped-cell-values -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 24, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-78209', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-24T18:02:14.458123Z'} -
New CVE Received by [email protected]
Aug. 24, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'exceljs', 'product': 'exceljs', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'semver', 'lessThanOrEqual': '4.4.0'}], 'packageURL': 'pkg:npm/exceljs', 'packageName': 'exceljs', 'collectionURL': 'https://www.npmjs.com/package/exceljs', 'defaultStatus': 'unaffected'}] Added 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. Added CVSS V4.0 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 Added CVSS V3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N Added CWE CWE-1236 Added Reference https://github.com/exceljs/exceljs Added Reference https://github.com/exceljs/exceljs/blob/v4.4.0/lib/csv/csv.js#L109-L182 Added Reference https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-9wxc-4rhw-hfrw Added Reference https://www.vulncheck.com/advisories/exceljs-through-csv-formula-injection-via-unescaped-cell-values