CVE-2026-128346

Description

ExcelJS through 4.4.0 contains a resource leak vulnerability in the streaming WorkbookReader.parse that leaves temporary files and open descriptors when sheet parsing fails or iteration stops early. Attackers can repeatedly upload malformed multi-sheet workbooks with worksheets placed before xl/sharedStrings.xml to fill the temporary directory and exhaust file descriptors.

References

• https://github.com/exceljs/exceljs
• https://github.com/exceljs/exceljs/blob/v4.4.0/lib/stream/xlsx/workbook-reader.js#L111-L128
• https://github.com/exceljs/exceljs/blob/v4.4.0/lib/stream/xlsx/workbook-reader.js#L140-L149
• https://github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-mp7v-gxhv-42h2
• https://www.vulncheck.com/advisories/exceljs-through-4.4.0-resource-exhaustion-via-streaming-workbookreader-temporary-files