CVE-2026-79591

High severity, CVSS 7.8. EPSS: 0.2% chance of exploitation in the next 30 days.

A heap-buffer-overflow and use-after-free vulnerability exists in the xls_getCSS() function of libxls 1.6.3 due to insufficient validation of a file-controlled font index.

Published 2026-09-10. Last modified 2026-09-22.