CVE-2026-59933
PhpSpreadsheet: XLS/OLE sector-chain self-loop causes memory exhaustion
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
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.
Public exploit
A reference of the record is tagged as an exploit or proof of concept: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: a proof of concept is public.
- https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-xh5m-36r6-47m3 (opens in a new tab)x_refsource_CONFIRMexploit
Timeline
ID reserved
By GitHub_M
- 21 days later
· 21 days later
Published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| NVDNVD · Deferred | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.46% · top 60% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: yes · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Weakness
Affected products
- affected >= 4.0.0, < 5.8.1
- affected >= 3.3.0, < 3.10.7
- affected >= 2.2.0, < 2.4.7
- affected >= 2.0.0, < 2.1.18
- affected < 1.30.6
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Packagistphpoffice/phpspreadsheetGHSA-xh5m-36r6-47m3 (opens in a new tab)
References (7)
- https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-xh5m-36r6-47m3 (opens in a new tab)x_refsource_CONFIRMexploit
- https://github.com/PHPOffice/PhpSpreadsheet/commit/85f2556b0bf5269061bf45932ecda8a128d81750 (opens in a new tab)x_refsource_MISC
- https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/1.30.6 (opens in a new tab)x_refsource_MISC
- https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/2.1.18 (opens in a new tab)x_refsource_MISC
- https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/2.4.7 (opens in a new tab)x_refsource_MISC
- https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/3.10.7 (opens in a new tab)x_refsource_MISC
- https://github.com/PHPOffice/PhpSpreadsheet/releases/tag/5.8.1 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-xh5m-36r6-47m3 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-59933)Record last updated .