What is CVE-2026-56406?

CVE-2026-56406 is a medium-severity vulnerability in Libexpat Project, classified under Integer Overflow or Wraparound. CVSS score: 6.9/10. Published 2026-06-21.

How severe is CVE-2026-56406?

Medium severity. CVSS v3 base score is 6.9 out of 10.

Integer overflow in Libexpat Project

CVE-2026-56406

libexpat before 2.8.2 has an integer overflow in XML_ParseBuffer because it lacked a check that was present in XML_Parse.

Vulnerability class: Integer Overflow

EPSS: 0.001 (3.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.9 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L.

Affected products

Libexpat Project — versions 0
Libexpat_project Libexpat

Weakness classification (CWE)

CWE-190 — Integer Overflow or Wraparound

References

cve@mitre.org (Patch, Issue Tracking)

Frequently asked questions

What is CVE-2026-56406?: CVE-2026-56406 is a medium-severity vulnerability in Libexpat Project, classified under Integer Overflow or Wraparound. CVSS score: 6.9/10. Published 2026-06-21.
How severe is CVE-2026-56406?: Medium severity. CVSS v3 base score is 6.9 out of 10.