Integer overflow in Libexpat Project

CVE-2026-56405

libexpat before 2.8.2 has an integer overflow in getAttributeId.

Vulnerability class: Integer Overflow

Published · last modified .

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.

EPSS exploit prediction

EPSS: 0.001 (1.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 2nd percentile — 1.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-56405: held from 0.001 to 0.001.

EPSS over last 30 days · oldest: 0.001 · newest: 0.001 · change: -0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-56405?
CVE-2026-56405 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-2026-56405?
Medium severity. CVSS v3 base score is 6.9 out of 10.