ExcelJS through 4.4.0 contains a resource leak vulnerability in the streaming WorkbookReader.parse that leaves
Source GCVE Database
Not known to be exploited · CVSS 8.7 High.
Data as of 13 Nov 2026, 13:24 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
Since this is a local resource exhaustion vulnerability, mitigation could include limiting file upload sizes, validating workbook structure before processing, or isolating the parsing environment to prevent system-wide impact. Monitor vendor advisories for official patches or updates addressing this issue.
Description
ExcelJS versions through 4.4.0 have a resource leak vulnerability in the streaming WorkbookReader.parse function. This flaw causes temporary files and open file descriptors to remain when sheet parsing fails or iteration stops early. An attacker can exploit this by uploading malformed multi-sheet workbooks with worksheets placed before xl/sharedStrings.xml, leading to exhaustion of temporary directory space and file descriptors.
References
- github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-mp7v-gxhv-42h2 (opens in a new tab)
- nvd.nist.gov/vuln/detail/CVE-2026-128346 (opens in a new tab)
- github.com/exceljs/exceljs (opens in a new tab)
- github.com/exceljs/exceljs/blob/v4.4.0/lib/stream/xlsx/workbook-reader.js (opens in a new tab)
- github.com/exceljs/exceljs/blob/v4.4.0/lib/stream/xlsx/workbook-reader.js (opens in a new tab)
- vulncheck.com/advisories/exceljs-through-4.4.0-resource-exhaustion-via-streaming-workbookreader-temporary-files (opens in a new tab)