CVE-2026-56409 Integer overflow in libexpat
An integer overflow in libexpat's xmlwf tool can cause denial of service when processing output filenames with a specified directory.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-56409?
CVE-2026-56409 is a medium-severity vulnerability in Libexpat Project Libexpat, published on 21 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
xmlwf in libexpat before 2.8.2 has an integer overflow for the output filename when -d outputDir is used.
Weakness: CWE-190
Which versions are affected by CVE-2026-56409?
It affects 1 product.
Products include Libexpat Project Libexpat.
How do I fix CVE-2026-56409?
Upgrade to a fixed version.
Is CVE-2026-56409 being exploited?
There is no known exploitation of CVE-2026-56409 in the wild and no public exploit code.
Other vulnerabilities in Libexpat Project Libexpat
Sources
Also known as ALPINE-CVE-2026-56409, AZL-90249, BELL-CVE-2026-56409, DEBIAN-CVE-2026-56409, ECHO-e231-2b20-a715, GHSA-jhv6-83wh-9vj5 and 3 more.