CVE-2026-56403: Integer Overflow
Published Jun 21, 2026
·Updated
Last updated 21 September 2026
Other sources
libexpat before 2.8.2 has an integer overflow in storeAtts.
— MITRE
Affected Software
4 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
debian/expat<=2.5.0-1+deb12u2
2.5.0-1+deb12u32.8.3-1~deb13u12.8.4-12.8.4-2
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 - Upgrade
Upgrade
debian/expatto a version that resolves this vulnerability.Fixed in 2.5.0-1+deb12u3Fixed in 2.8.3-1~deb13u1Fixed in 2.8.4-1Fixed in 2.8.4-2 - Upgrade
Upgrade
libexpatto a version that resolves this vulnerability.Fixed in 2.8.2
Event History
Jun 21, 2026
CVE Published
via MITRE·03:43 PM
Data Sourced
via MITRE·03:43 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
Sep 21, 2026
Data Sourced
via Launchpad·06:54 PM
Description
Sep 22, 2026
Data Sourced
via Ubuntu·06:54 PM
RemedyDescriptionSeverityAffected Software
Data Sourced
via Debian·06:56 PM
DescriptionAffected Software
Frequently Asked Questions
1
What is the severity of CVE-2026-56403?
CVE-2026-56403 has a severity score of 6.9, classifying it as medium risk.
2
What type of vulnerability is identified by CVE-2026-56403?
CVE-2026-56403 is classified as an integer overflow vulnerability.
3
How do I fix CVE-2026-56403?
To fix CVE-2026-56403, update to Expat version 2.8.2 or later.
4
Which software is affected by CVE-2026-56403?
CVE-2026-56403 affects the Expat library version prior to 2.8.2.
5
What are the potential impacts of CVE-2026-56403?
The integer overflow in CVE-2026-56403 could lead to elevated privileges and data corruption.