CVE-2026-56411

expat: libexpat: Integer Overflow Vulnerability Leading to Information Disclosure or Code Execution

Published Jun 21, 2026 CVSS 3.1 · 6.9 Medium EPSS < 1% KEV · Not listed
Description
xmlwf in libexpat before 2.8.2 has an integer overflow in endDoctypeDecl via NOTATION declarations.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4765-1 expat security update
Debian DSA Debian DSA DSA-6404-1 expat security update
History
Type Values Removed Values Added
Title Integer Overflow in XML Notation Declaration Parsing expat: libexpat: Integer Overflow Vulnerability Leading to Information Disclosure or Code Execution
References
Metrics threat_severity

None

threat_severity

Moderate

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Title Integer Overflow in XML Notation Declaration Parsing
Type Values Removed Values Added
Description xmlwf in libexpat before 2.8.2 has an integer overflow in endDoctypeDecl via NOTATION declarations.
First Time appeared Libexpat Project
Libexpat Project libexpat
Weaknesses CWE-190
CPEs cpe:2.3:a:libexpat_project:libexpat:*:*:*:*:*:*:*:*
Vendors & Products Libexpat Project
Libexpat Project libexpat
References
Metrics cvssV3_1

{'score': 6.9, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
mitre
Published
Updated
Nov 10, 2026, 12:48 PM
Reserved
Jun 21, 2026, 3:56 PM
Status
Modified
Published
Jun 21, 2026, 5:16 PM
Modified
Nov 10, 2026, 1:19 PM
Severity
Moderate
Public date
Jun 21, 2026, 3:56 PM