Buffer overflow in N/a

CVE-2026-79591

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.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.002 (6.8th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 6.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-79591: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-79591?
CVE-2026-79591 is a high-severity vulnerability in N/a, classified under Heap-based Buffer Overflow. CVSS score: 7.8/10. Published 2026-09-10.
How severe is CVE-2026-79591?
High severity. CVSS v3 base score is 7.8 out of 10.