CVE-2026-56406: Integer Overflow
Published Jun 21, 2026
·Updated
libexpat before 2.8.2 has an integer overflow in XMLParseBuffer because it lacked a check that was present in XMLParse.
Affected Software
3 affected componentsFixes available
Expat libexpat<2.8.2
Libexpat Project Libexpat<2.8.2
Microsoft azl3 expat 2.6.4-6<2.8.2-1
2.8.2-1
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 2.8.2-1
Event History
Jun 21, 2026
CVE Published
via MITRE·03:48 PM
Data Sourced
via MITRE·03:48 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·04:16 PM
RemedyDescriptionSeverityWeaknessAffected Software
Jun 27, 2026
Data Sourced
via Microsoft·08:05 AM
DescriptionSeverityWeaknessAffected Software
Updated
via Microsoft·08:05 AM
DescriptionSeverity
Frequently Asked Questions
1
What is the severity of CVE-2026-56406?
The severity of CVE-2026-56406 is classified as medium with a score of 6.9.
2
What is CVE-2026-56406 related to in libexpat?
CVE-2026-56406 is related to an integer overflow vulnerability in XML_ParseBuffer in libexpat before version 2.8.2.
3
How do I fix CVE-2026-56406?
To fix CVE-2026-56406, update libexpat to version 2.8.2 or later.
4
What is the impact of CVE-2026-56406?
The impact of CVE-2026-56406 includes potential data corruption and denial of service due to the integer overflow.
5
Which versions of libexpat are affected by CVE-2026-56406?
Versions of libexpat before 2.8.2 are affected by CVE-2026-56406.