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CVE-2026-128346VulnerabilityPublished

ExcelJS through 4.4.0 contains a resource leak vulnerability in the streaming WorkbookReader.parse that leaves

Source GCVE Database

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Authoritative record:CVE-2026-128346· High 8.7

Not known to be exploited · CVSS 8.7 High.

Data as of 13 Nov 2026, 13:24 UTC

CVSS 4.0 base score
8.7High
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.08.7
CNA (VulnCheck)CVSS 3.17.5
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 13 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
exceljsexceljsAffected
  • <=4.4.0
Fixed in–
npmexceljspkg:npm/exceljsOther threatsAffected
  • <=4.4.0
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

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