CVE-2026-78206

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.

Scoring

Severity
HIGH
CVSS base score
8.7
CVSS vector
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
EPSS probability
0.45%
CWE
CWE-409
Published
2026-08-24
Last modified
2026-08-29

Affected products

Weakness type

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