Vulnerability Description
PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. Prior to 1.30.4, 2.1.16, 2.4.5, 3.10.5, and 5.7.0, the SpreadsheetML XML reader (Reader\Xml) does not validate the ss:Index row attribute against the maximum allowed row count (AddressRange::MAX_ROW = 1,048,576). An attacker can craft a SpreadsheetML XML file with ss:Index="999999999" on a <Row> element, which inflates the internal cachedHighestRow to ~1 billion. Any subsequent call to getRowIterator() without an explicit end row will attempt to iterate ~1 billion rows, causing CPU exhaustion and denial of service. This vulnerability is fixed in 1.30.4, 2.1.16, 2.4.5, 3.10.5, and 5.7.0.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Phpoffice | Phpspreadsheet | < 1.30.4 |
Related Weaknesses (CWE)
References
- https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-84wq-86v6-xExploitMitigationVendor Advisory
- https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-84wq-86v6-xExploitMitigationVendor Advisory
FAQ
What is CVE-2026-40863?
CVE-2026-40863 is a vulnerability with a CVSS score of 7.5 (HIGH). PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. Prior to 1.30.4, 2.1.16, 2.4.5, 3.10.5, and 5.7.0, the SpreadsheetML XML reader (Reader\Xml) does not validate the ss:In...
How severe is CVE-2026-40863?
CVE-2026-40863 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-40863?
Check the references section above for vendor advisories and patch information. Affected products include: Phpoffice Phpspreadsheet.