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VulnerabilityPublished

CVE-2026-128343: exceljs · Unchecked Input for Loop Condition

Affects exceljsSource CVE Database V5

0
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Not known to be exploited · CVSS 8.7 High.

Data as of 13 Nov 2026, 09:44 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

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

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