What is CVE-2026-35453?

CVE-2026-35453 is a medium-severity vulnerability in Phpoffice Phpspreadsheet, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-05-05.

How severe is CVE-2026-35453?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Phpoffice Phpspreadsheet

CVE-2026-35453

PhpSpreadsheet is a library for reading and writing spreadsheet files. In versions 1.30.3 and earlier, 2.0.0 through 2.1.15, 2.2.0 through 2.4.4, 3.3.0 through 3.10.4, and 4.0.0 through 5.6.0, the HTML Writer skips htmlspecialchars() outpu…

Vulnerability class: XSS (Cross-Site Scripting)

EPSS: 0.000 (1.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

Affected products

Phpoffice Phpspreadsheet — versions >= 4.0.0, <= 5.6.0, >= 3.3.0, <= 3.10.4, >= 2.2.0, <= 2.4.4

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

https://github.com/PHPOffice/PhpSpreadsheet/security/advisories/GHSA-6wpp-88cp-7q68 (x_refsource_CONFIRM, Exploit, Vendor Advisory)

Frequently asked questions

What is CVE-2026-35453?: CVE-2026-35453 is a medium-severity vulnerability in Phpoffice Phpspreadsheet, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-05-05.
How severe is CVE-2026-35453?: Medium severity. CVSS v3 base score is 5.4 out of 10.