CVE-2026-40902
7.5 · HIGHOverview
CVE-2026-40902 is a high-severity vulnerability affecting phpoffice phpspreadsheet. It was published on May 12, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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 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.
Remediation
Check the references section for vendor advisories and patches from phpoffice. Update phpspreadsheet to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| phpoffice | phpspreadsheet | >= 0, < 1.30.4 | Affected |
Frequently Asked Questions
What is CVE-2026-40902?
CVE-2026-40902 is a high-severity vulnerability affecting phpoffice phpspreadsheet. It was published on May 12, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-40902?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-40902?
Check the references section for vendor advisories and patches from phpoffice. Update phpspreadsheet to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-40902?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-40902 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
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