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Fencer Intel
high 7.5

CVE-2026-40863 json

PhpSpreadsheet: CPU Denial of Service via Unbounded Row Index in SpreadsheetML XML Reader

published 6mo ago modified 14d ago also EUVD-2026-29851 , GHSA-84wq-86v6-x5j6

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 33%
public exploits
0
none known

Summary

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.

Patch / fix

  • packagist phpoffice/phpspreadsheet 1.30.6, 2.1.16, 2.4.5, 3.10.5, 5.7.0
  • phpoffice phpspreadsheet 1.30.4, 2.1.16, 2.4.5, 3.10.5, 5.7.0
  • phpspreadsheet_project phpspreadsheet 1.30.4, 2.1.16, 2.4.5, 3.10.5, 5.7.0

Is CVE-2026-40863 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
5mo ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 33% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-84wq-86v6-x5j6 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
packagist phpoffice/phpspreadsheet
>=4.0.0, <5.7.0
>=3.3.0, <3.10.5
>=2.2.0, <2.4.5
>=2.0.0, <2.1.16
<1.30.6
5.7.0
3.10.5
2.4.5
2.1.16
1.30.6

Affected products

  • PHPOffice PhpSpreadsheet

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.