High severity7.5NVD Advisory· Published Aug 24, 2026

CVE-2026-78206

Description

exceljs-hardened before 5.0.0 decompresses all entries from supplied xlsx archives into memory without limits on entry size, total size, or compression ratio. Attackers can upload highly compressed workbooks that expand to gigabytes in memory, exhausting available resources and causing denial of service.

Affected products

Exceljs Project/Exceljsllm-fuzzy
Range: <5.0.0
Mateocallec/exceljs-hardenedllm-create
Range: <5.0.0

Patches

Vulnerability mechanics

References

github.com/exceljs/exceljs/blob/v4.4.0/lib/xlsx/xlsx.jsnvd
github.com/mateocallec/exceljs-hardened/security/advisories/GHSA-7cvf-3r55-r39qnvd
www.vulncheck.com/advisories/exceljs-through-uncontrolled-resource-consumption-via-unbounded-xlsx-decompressionnvd

News mentions

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