Instituto Nacional de ciberseguridad. Sección Incibe
Instituto Nacional de Ciberseguridad. Sección INCIBE-CERT

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CVE-2026-79591

Severity CVSS v4.0:
Pending analysis
Type:
CWE-122 Heap-based Buffer Overflow
Publication date:
10/09/2026
Last modified:
22/09/2026

Description

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.

Impact

Vector 3.x
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H CVSS v3.1 Severity and Metrics:

Base Score: 7.80 HIGH
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Attack Vector (AV): Local
Attack Complexity (AC): Low
Privileges Required (PR): None
User Interaction (UI): Required
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): High
Availability (A): High

Base Score 3.x
7.80
Severity 3.x
HIGH

References to Advisories, Solutions, and Tools