CVE-2026-128342: 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.
Description
ExcelJS versions up to 4.4.0 have a denial of service vulnerability due to unchecked input for a loop condition. An attacker can supply a workbook with an excessively large sheetId in xl/workbook.xml, causing the event loop to block and operations like worksheet traversal and buffer writing to stall for extended periods.
References
- github.com/exceljs/exceljs (opens in a new tab)
- github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-9vv6-5g3h-prg5 (opens in a new tab)
- github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/workbook.js (opens in a new tab)
- github.com/exceljs/exceljs/blob/v4.4.0/lib/doc/workbook.js (opens in a new tab)
- vulncheck.com/advisories/exceljs-through-4.4.0-denial-of-service-via-oversized-worksheet-sheetid (opens in a new tab)