CVE-2026-79591 Details
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.
A heap-buffer-overflow and use-after-free vulnerability has been identified in libxls version 1.6.3. This issue arises in the xls_getCSS() function, where insufficient validation of a file-controlled font index allows for out-of-bounds access. The vulnerability can be exploited by crafting an OLE2/BIFF .xls file that manipulates the font index, leading to memory corruption.
Users are advised to update to the latest version of libxls, where this vulnerability has been addressed by validating font indices before they are used.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Sep 10, 2026CISA-ADP
Assessed Sep 15, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/libxls/libxls/issues/161 | CISA-ADP | ExploitIssue TrackingTechnical DescriptionVendor |
| https://github.com/libxls/libxls/issues/161 | [email protected] | ExploitIssue TrackingTechnical DescriptionVendor |
| https://github.com/libxls/libxls/pull/164/changes/902c8f9b13710c3a13b6232fb86626c5c729402c | [email protected] | Source CodeVendor |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-122 | Heap-based Buffer Overflow | CISA-ADP |
Affected Products
| Product | Versions |
|---|---|
| libxls | 1.6.3 (semver) |
CPE
Remediation
| |
Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Sep 15, 2026 | CVE Modified | CISA-ADP |
| Sep 10, 2026 | New CVE Received | [email protected] |