What is CVE-2026-56407?

CVE-2026-56407 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-2026-56407?

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

Integer overflow in Libexpat Project

CVE-2026-56407

libexpat before 2.8.2 has an integer overflow in doProlog that is related to storeEntityValue and entity textLen.

Vulnerability class: Integer Overflow

Published 2026-06-21 · last modified 2026-10-25.

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: 0.002 (6.9th percentile), scored 2026-11-04.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 6.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000

Affected products

Libexpat Project — versions 0
Libexpat Project

Weakness classification (CWE)

CWE-190 — Integer Overflow or Wraparound

References

github.com/libexpat/libexpat/pull/1262 (Patch, Issue Tracking)

Frequently asked questions

What is CVE-2026-56407?: CVE-2026-56407 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-2026-56407?: Medium severity. CVSS v3 base score is 6.9 out of 10.