CVE-2026-56409: Integer Overflow
Published Jun 21, 2026
·Updated
xmlwf in libexpat before 2.8.2 has an integer overflow for the output filename when -d outputDir is used.
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·03:52 PM
Data Sourced
via MITRE·03:52 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·04:16 PM
RemedyDescriptionSeverityWeaknessAffected Software
Jun 27, 2026
Data Sourced
via Microsoft·08:06 AM
DescriptionSeverityWeaknessAffected Software
Updated
via Microsoft·08:06 AM
DescriptionSeverity
Frequently Asked Questions
1
What is the severity of CVE-2026-56409?
The severity of CVE-2026-56409 is medium, rated at 6.5.
2
What kind of vulnerability is CVE-2026-56409?
CVE-2026-56409 is classified as an integer overflow vulnerability.
3
How does CVE-2026-56409 affect software?
CVE-2026-56409 affects the Expat library's xmlwf tool when it is used with the -d outputDir option.
4
How do I fix CVE-2026-56409?
To fix CVE-2026-56409, upgrade to libexpat version 2.8.2 or later.
5
What can be the consequences of exploiting CVE-2026-56409?
Exploiting CVE-2026-56409 may lead to potential denial of service or disclosure of sensitive information.