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Fencer Vulns
high 7.5

CVE-2026-59933 json

PhpSpreadsheet: XLS/OLE sector-chain self-loop causes memory exhaustion

published 2026-07-23 3 mo ago modified 2026-10-23 16 d ago also EUVD-2026-49930 , GHSA-xh5m-36r6-47m3

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits
0
none known

Summary

PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. In versions 4.0.0 through 5.8.0, 3.3.0 through 3.10.6, 2.2.0 through 2.4.6, 2.0.0 through 2.1.17, and all releases up to and including 1.30.5, the OLE reader follows sector chains from attacker-controlled XLS/OLE metadata without detecting cycles or enforcing a maximum chain length. A tiny malformed .xls/OLE file can set the small-block depot sector chain to point back to itself. During normal XLS detection, OLERead::read() appends the same sector data repeatedly until the PHP process exhausts memory. This is reachable from Reader\Xls::canRead() and therefore from automatic spreadsheet type detection. Applications that accept attacker-controlled spreadsheet uploads can suffer denial of service from a very small file. This issue has been fixed in versions 5.8.1, 3.10.7, 2.4.7, 2.1.18 and 1.30.6.

Patch / fix

  • packagist phpoffice/phpspreadsheet 1.30.6, 2.1.18, 2.4.7, 3.10.7, 5.8.1
  • phpoffice phpspreadsheet 1.30.6, 2.1.18, 2.4.7, 3.10.7, 5.8.1
  • phpspreadsheet_project phpspreadsheet 1.30.6, 2.1.18, 2.4.7, 3.10.7, 5.8.1

CISA SSVC

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

Exploit prediction

0.46% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-xh5m-36r6-47m3 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, <5.8.1
>=3.3.0, <3.10.7
>=2.2.0, <2.4.7
>=2.0.0, <2.1.18
<1.30.6
5.8.1
3.10.7
2.4.7
2.1.18
1.30.6

Affected products

  • PHPOffice PhpSpreadsheet

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-835 Loop with Unreachable Exit Condition

References

Sources

Fencer Vulns 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.