Service interruption via unbounded SpreadsheetML row index
Published May 12, 2026 · Updated May 12, 2026
Resource exhaustion in PHPOffice PhpSpreadsheet affected releases allows remote attackers to hang PHP workers through crafted SpreadsheetML XML files. The Reader\Xml loadSpreadsheetFromFile method accepts an ss:Index row value above AddressRange::MAX_ROW, stores it as cachedHighestRow, and makes a default getRowIterator() traverse roughly one billion rows. Exploitation requires an application to process an attacker-controlled SpreadsheetML file and iterate rows without an explicit end; confidentiality and integrity remain unaffected.
Summary
What happened
Resource exhaustion in PHPOffice PhpSpreadsheet affected releases allows remote attackers to hang PHP workers through crafted SpreadsheetML XML files. The Reader\Xml loadSpreadsheetFromFile method accepts an ss:Index row value above AddressRange::MAX_ROW, stores it as cachedHighestRow, and makes a default getRowIterator() traverse roughly one billion rows. Exploitation requires an application to process an attacker-controlled SpreadsheetML file and iterate rows without an explicit end; confidentiality and integrity remain unaffected.
The record
- CVE
- CVE-2026-40863
- Published
- May 12, 2026
- Updated
- May 12, 2026
- Vendor
- PHPOffice
- Product
- PhpSpreadsheet
- Classifications
- CWE-770, CWE-400, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 12, 2026CVE publishedPublication date reported by the CVE source.
- May 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 1.30.4
- Affected versionversion=>= 2.0.0, < 2.1.16
- Affected versionversion=>= 2.2.0, < 2.4.5
- Affected versionversion=>= 3.3.0, < 3.10.5
- Affected versionversion=>= 4.0.0, < 5.7.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- SpreadsheetML unbounded row-index proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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