ExcelJS through 4.4.0 contains a denial of service vulnerability that allows attackers to block the event loop by supplying an unbounded sheetId in xl/workbook.xml. Attackers can provide a workbook with a huge sheetId, making the sparse worksheet array walk stall worksheets, getWorksheet and writeBuffer for seconds.
{
"cna_assigner": "VulnCheck",
"cwe_ids": [
"CWE-606"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/128xxx/CVE-2026-128342.json"
}{
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"last_affected": "4.4.0"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StandardRange"
}
]
}