What is CVE-2026-34084?

CVE-2026-34084 is a critical-severity vulnerability in Phpoffice Phpspreadsheet, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2026-05-05.

How severe is CVE-2026-34084?

Critical severity. CVSS v3 base score is 9.8 out of 10.

SSRF in Phpoffice Phpspreadsheet

CVE-2026-34084

PhpSpreadsheet is a library for reading and writing spreadsheet files. In versions 1.30.2 and earlier, 2.0.0 through 2.1.14, 2.2.0 through 2.4.3, 3.3.0 through 3.10.3, and 4.0.0 through 5.5.0, when the filename argument to IOFactory::load(…

Vulnerability class: Insecure Deserialization

EPSS: 0.002 (45.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Affected products

Phpoffice Phpspreadsheet — versions >= 4.0.0, <= 5.5.0, >= 3.3.0, <= 3.10.3, >= 2.2.0, <= 2.4.3

Weakness classification (CWE)

References

https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-q4q6-r8wh-5cgh (x_refsource_CONFIRM, Exploit, Mitigation, Vendor Advisory)

Frequently asked questions

What is CVE-2026-34084?: CVE-2026-34084 is a critical-severity vulnerability in Phpoffice Phpspreadsheet, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2026-05-05.
How severe is CVE-2026-34084?: Critical severity. CVSS v3 base score is 9.8 out of 10.