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

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.

Timeline

1. Jul 28, 2026, 5:29 PM UTCCVE published
2. Jul 28, 2026, 5:57 PM UTCCISA SSVC assessment

   Exploitation: poc · Automatable: yes · Technical impact: partial

3. Jul 28, 2026, 5:57 PM UTCRecord last updated

Affected versions

• PHPOffice PhpSpreadsheet

  From 4.0.0 · fixed in 5.8.1; From 3.3.0 · fixed in 3.10.7; From 2.2.0 · fixed in 2.4.7; From 2.0.0 · fixed in 2.1.18; fixed in 1.30.6

• phpoffice/phpspreadsheetPackagist

  From 4.0.0 · fixed in 5.8.1

• phpoffice/phpspreadsheetPackagist

  From 3.3.0 · fixed in 3.10.7

• phpoffice/phpspreadsheetPackagist

  From 2.2.0 · fixed in 2.4.7

• phpoffice/phpspreadsheetPackagist

  From 2.0.0 · fixed in 2.1.18

• phpoffice/phpspreadsheetPackagist

  fixed in 1.30.6

References 7