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

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...

PT-2026-63656

Name of the Vulnerable Software and Affected Versions PhpSpreadsheet affected versions not specified Description The OLE reader in PhpSpreadsheet follows sector chains from XLS/OLE metadata without detecting cycles or enforcing a maximum chain length. A malformed file can set the small-block depo...