Integer overflow in expat - CVE-2026-56403

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Main Vulnerability Database Vulnerabilities #VU144341

Integer overflow in expat - CVE-2026-56403

Published: August 19, 2026


Vulnerability identifier: #VU144341
CSH Severity: Medium
CVSS v4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-56403
CWE-ID: CWE-190
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to cause memory corruption.

The vulnerability exists due to an integer overflow in storeAtts when parsing XML attributes. A remote attacker can supply crafted XML input to cause memory corruption.


Affected software

expat
Debian Linux
Ubuntu
openEuler
Anolis OS
LANTIME Operating System Firmware (LTOS)
expat (Ubuntu package)
expat
expat-help
expat-devel
expat-debugsource
expat-debuginfo
expat-doc
expat-static
expat (Debian package)

How to mitigate CVE-2026-56403

Install security update from vendor's website.

expat - update to 2.8.2
LANTIME Operating System Firmware (LTOS) - update to 7.10.013
expat (Ubuntu package) - addressed in versions 2.1.0-4ubuntu1.4+esm12, 2.1.0-7ubuntu0.16.04.5+esm13, 2.2.5-3ubuntu0.9+esm4, 2.2.9-1ubuntu0.8+esm2, 2.4.7-1ubuntu0.8, 2.6.1-2ubuntu0.5, 2.7.4-1ubuntu0.1
expat - addressed in versions 2.2.9-28, 2.4.1-27, 2.5.0-22, 2.5.0-23
expat-help - addressed in versions 2.2.9-28, 2.4.1-27, 2.5.0-22, 2.5.0-23
expat-devel - addressed in versions 2.2.9-28, 2.4.1-27, 2.5.0-22, 2.5.0-23
expat-debugsource - addressed in versions 2.2.9-28, 2.4.1-27, 2.5.0-22, 2.5.0-23
expat-debuginfo - addressed in versions 2.2.9-28, 2.4.1-27, 2.5.0-22, 2.5.0-23
expat-doc - update to 2.5.0-18
expat-static - update to 2.5.0-18
expat - update to 2.5.0-18
expat-devel - update to 2.5.0-18
expat (Debian package) - update to 2.8.2-1~deb13u1

External References

Related Security Bulletins