CVE-2026-56132

expat: libexpat: Arbitrary Code Execution via Heap-based Buffer Overflow

Published Jun 19, 2026 CVSS 3.1 · 6.9 Medium EPSS < 1% KEV · Not listed
Description
In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold backing array reallocation is mishandled when there is data-structure sharing across parsers.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4849-1 expat security update
Debian DSA Debian DSA DSA-6404-1 expat security update
History
Type Values Removed Values Added
Title Heap-Based Buffer Overflow in libexpat XML Parser expat: libexpat: Arbitrary Code Execution via Heap-based Buffer Overflow
Weaknesses CWE-131
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 Heap-Based Buffer Overflow in libexpat XML Parser
Type Values Removed Values Added
Description In libexpat before 2.8.2, there is a heap-based buffer overflow in doProlog in xmlparse.c because scaffold backing array reallocation is mishandled when there is data-structure sharing across parsers.
First Time appeared Libexpat Project
Libexpat Project libexpat
Weaknesses CWE-821
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 19, 2026, 3:00 AM
Status
Modified
Published
Jun 19, 2026, 6:17 AM
Modified
Nov 10, 2026, 1:19 PM
Severity
Moderate
Public date
Jun 19, 2026, 3:00 AM