Vulnerability · Published Aug 24, 2026 · Assigned by VulnCheck
CVE-2026-78206exceljs through 4.4.0 Uncontrolled Resource Consumption via Unbounded xlsx Decompression
High 7.5
In plain English
A high-severity security flaw in exceljs from exceljs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 50% of all known vulnerabilities).
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.6%top 49.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
exceljs through 4.4.0 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 (as reported)
Weakness: CWE-409 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/exceljs/exceljs product
- GitHub Security Advisory (GHSA-7cvf-3r55-r39q) third-party-advisory
- https://github.com/exceljs/exceljs/blob/v4.4.0/lib/xlsx/xlsx.js#L257-L281 technical-description
- VulnCheck Advisory: exceljs through 4.4.0 Uncontrolled Resource Consumption via Unbounded xlsx Decompression third-party-advisory