GHSA-xh5m-36r6-47m3: phpoffice/phpspreadsheet (CVE-2026-59933)

Package	Ecosystem	Affected	Fixed in
phpoffice/phpspreadsheet	Packagist	>=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	5.8.1, 3.10.7, 2.4.7, 2.1.18, 1.30.6

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

PhpSpreadsheet versions below 1.30.6, from 2.0.0 to below 2.1.18, from 2.2.0 to below 2.4.7, from 3.3.0 to below 3.10.7, and from 4.0.0 to below 5.8.1 are vulnerable. A remote attacker can supply a very small malformed XLS/OLE file whose sector chain loops back on itself, causing memory exhaustion during file-type detection and crashing the PHP process, which denies service to applications that accept untrusted spreadsheet uploads. Upgrade to 1.30.6, 2.1.18, 2.4.7, 3.10.7, or 5.8.1 or later. The source gives no workaround.

Written 3 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
7.5	High	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0046, the 40th percentile, on 14 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

31 Oct 2026, 14:24 UTC First seen by agentprime
31 Oct 2026, 14:24 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.