CVE-2026-128343: exceljs · Unchecked Input for Loop Condition
Affects exceljsSource CVE Database V5
Not known to be exploited · CVSS 8.7 High.
Data as of 13 Nov 2026, 09:44 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 8.7 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 7.5 |
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 13 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| exceljsexceljs | Affected
| Fixed in– |
npmexceljspkg:npm/exceljsOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Until a fix is available, avoid processing untrusted XLSX files with exceljs or implement input validation to limit row numbers.
Description
A denial of service vulnerability exists in exceljs up to version 4.4.0 where unbounded row numbers in XLSX files can cause excessive processing time. This occurs because the library does not properly check input used in loop conditions when parsing row attributes, leading to event loop blocking during operations like getSheetValues(), workbook writes, and CSV exports.
References
- github.com/exceljs/exceljs (opens in a new tab)
- github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-3gm5-qxj8-89rr (opens in a new tab)
- github.com/exceljs/exceljs/blob/v4.4.0/lib/xlsx/xform/sheet/row-xform.js (opens in a new tab)
- github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/worksheet.js (opens in a new tab)
- github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/worksheet.js (opens in a new tab)
- vulncheck.com/advisories/exceljs-through-4.4.0-denial-of-service-via-oversized-row-number (opens in a new tab)