High 7.5Published Jul 28, 2026

CVE-2026-59933PhpSpreadsheet: XLS/OLE sector-chain self-loop causes memory exhaustion

Updated under an hour ago (Oct 26, 2026, 11:40 PM ET)

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No exploitation reported and no EPSS estimate yet.

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Every CVE for PHPOffice PhpSpreadsheet

Exploited in the last 30 days

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.

CVSS: 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): CWE-400, CWE-835
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Jul 28, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

PHPOffice PhpSpreadsheet phpoffice:phpspreadsheet (from the name)	from 4.0.0, < 5.8.1; from 3.3.0, < 3.10.7; from 2.2.0, < 2.4.7; from 2.0.0, < 2.1.18; before 1.30.6	CNA record

References

References

https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-xh5m-36r6-47m3	x-refsource-confirm
https://github.com/PHPOffice/PhpSpreadsheet/commit/85f2556b0bf5269061bf45932ecda8a128d81750	x-refsource-misc
https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/1.30.6	x-refsource-misc
https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/2.1.18	x-refsource-misc
https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/2.4.7	x-refsource-misc
https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/3.10.7	x-refsource-misc
https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/5.8.1	x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.