Vulnerability · Published Jul 28, 2026 · Assigned by GitHub_M
CVE-2026-59933PhpSpreadsheet: XLS/OLE sector-chain self-loop causes memory exhaustion
High 7.5
In plain English
A high-severity uncontrolled resource consumption in PhpSpreadsheet from PHPOffice. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Packagist | phpoffice/phpspreadsheet | 5.8.1 | GHSA-xh5m-36r6-47m3 |
| Packagist | phpoffice/phpspreadsheet | 3.10.7 | GHSA-xh5m-36r6-47m3 |
| Packagist | phpoffice/phpspreadsheet | 2.4.7 | GHSA-xh5m-36r6-47m3 |
| Packagist | phpoffice/phpspreadsheet | 2.1.18 | GHSA-xh5m-36r6-47m3 |
| Packagist | phpoffice/phpspreadsheet | 1.30.6 | GHSA-xh5m-36r6-47m3 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| 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 |
Weakness: CWE-400, CWE-835 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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