CVE-2026-40296: PhpSpreadsheet has XSS via number format code with @ text placeholder bypasses htmlspecialchars in HTML writer

Ghostwire Analysis — What This Means Practically

• Medium CVSS score indicates moderate risk — exploitation requires specific conditions or results in limited impact.
• 1 proof-of-concept exploit available on GitHub. Public exploit code lowers the barrier for both researchers and attackers.

This analysis is generated by Ghostwire from NVD, CISA KEV, EPSS, and open-source intelligence data. Verify findings through primary sources before acting.