CVE-2026-26825

Use‑of‑Uninitialized Memory in libxls 1.6.3 During XLS Parsing

Published Jun 3, 2026 CVSS 3.1 · 5.3 Medium EPSS < 1% KEV · Not listed
Description
A use-of-uninitialized memory vulnerability exists in libxls 1.6.3 when parsing malformed XLS files. The issue is reachable via xls_parseWorkBook() and is triggered by uninitialized heap memory originating from the OLE layer (ole2_read). The flaw is detectable with MemorySanitizer (MSAN) and can lead to undefined behavior, incorrect parsing logic, or potential information disclosure.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

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History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Libxls
Libxls libxls
Vendors & Products Libxls
Libxls libxls
Type Values Removed Values Added
Title Use‑of‑Uninitialized Memory in libxls 1.6.3 During XLS Parsing
Type Values Removed Values Added
Title Uninitialized Memory Use in libxls 1.6.3 Leads to Undefined Behavior and Possible Information Disclosure
Weaknesses CWE-758
Type Values Removed Values Added
First Time appeared Libxls Project
Libxls Project libxls
Weaknesses CWE-908
CPEs cpe:2.3:a:libxls_project:libxls:1.6.3:*:*:*:*:*:*:*
Vendors & Products Libxls Project
Libxls Project libxls
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'}

Type Values Removed Values Added
Title Uninitialized Memory Use in libxls 1.6.3 Leads to Undefined Behavior and Possible Information Disclosure
Weaknesses CWE-758
Type Values Removed Values Added
Description A use-of-uninitialized memory vulnerability exists in libxls 1.6.3 when parsing malformed XLS files. The issue is reachable via xls_parseWorkBook() and is triggered by uninitialized heap memory originating from the OLE layer (ole2_read). The flaw is detectable with MemorySanitizer (MSAN) and can lead to undefined behavior, incorrect parsing logic, or potential information disclosure.
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Sep 23, 2026, 3:48 PM
Reserved
Feb 16, 2026, 12:00 AM
Status
Modified
Published
Jun 3, 2026, 8:16 PM
Modified
Sep 23, 2026, 4:16 PM