CVE-2026-40863
Last modified
CVE-2026-40863 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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). EPSS estimates a 0.40% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Phpoffice | Phpspreadsheet | < 1.30.4 |
| Phpoffice | Phpspreadsheet | >= 2.0.0, < 2.1.16 |
| Phpoffice | Phpspreadsheet | >= 2.2.0, < 2.4.5 |
| Phpoffice | Phpspreadsheet | >= 3.3.0, < 3.10.5 |
| Phpoffice | Phpspreadsheet | >= 4.0.0, < 5.7.0 |
References
- https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-84wq-86v6-x5j6Exploit, Mitigation, Vendor Advisory
- https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-84wq-86v6-x5j6Exploit, Mitigation, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-40863?
How severe is CVE-2026-40863?
How do I fix CVE-2026-40863?
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2026
- CVE-2026-40852A highly authenticated attacker can alter the config generat…7.2
- CVE-2026-40858The camel-infinispan component's ProtoStream-based remote ag…8.8
- CVE-2026-40859Deserialization of Untrusted Data vulnerability in Apache Ca…8.1
- CVE-2026-4086The WP Random Button plugin for WordPress is vulnerable to S…6.4
- CVE-2026-40860JmsBinding.extractBodyFromJms() in camel-jms, and the equiva…9.8
- CVE-2026-40861A Dag author could either (a) create a symlink under their t…6.5
- CVE-2026-40864JupyterHub is software that allows users to create a multi-u…4.3
- CVE-2026-40865Horilla is a free and open source Human Resource Management …7.1
- CVE-2026-40866Horilla is a free and open source Human Resource Management …8.6
- CVE-2026-40867Horilla is a free and open source Human Resource Management …7.1
- CVE-2026-40868Kyverno is a policy engine designed for cloud native platfor…8.1
- CVE-2026-40869Decidim is a participatory democracy framework. Starting in …6.5
Are you affected by CVE-2026-40863?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST