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Fencer Intel
high 7.5

CVE-2026-40902 json

PhpSpreadsheet: CPU Denial of Service via Unbounded Row Number in XLSX Row Dimensions

published 6mo ago modified 14d ago also EUVD-2026-29852 , GHSA-7c6m-4442-2x6m

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 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.

Patch / fix

  • packagist phpoffice/phpspreadsheet 1.30.4, 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-2026-40902 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-7c6m-4442-2x6m 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
<1.30.4
5.7.0
3.10.5
2.4.5
2.1.16
1.30.4

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.