CVE-2026-40902: Phpoffice Phpspreadsheet

High severity, CVSS 7.5. EPSS: 0.5% chance of exploitation in the next 30 days.

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 XLSX reader's ColumnAndRowAttributes::readRowAttributes() method reads row numbers from XML attributes without validating them against the spreadsheet maximum row limit (AddressRange::MAX_ROW = 1,048,576). An attacker can craft a minimal XLSX file (~1.6KB) containing a <row r="999999999"/> element that inflates cachedHighestRow to 999,999,999, causing any subsequent row iteration to attempt ~1 billion loop cycles and exhaust CPU resources. This vulnerability is fixed in 1.30.4, 2.1.16, 2.4.5, 3.10.5, and 5.7.0.

Affected products

• Phpoffice Phpspreadsheet: before 1.30.4 (fixed in 1.30.4); from 2.0.0, before 2.1.16 (fixed in 2.1.16); from 2.2.0, before 2.4.5 (fixed in 2.4.5); from 3.3.0, before 3.10.5 (fixed in 3.10.5); from 4.0.0, before 5.7.0 (fixed in 5.7.0)

Published 2026-05-12. Last modified 2026-06-17.