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Vulnerability · Published Jun 21, 2026 · Assigned by mitre

CVE-2026-56409

Medium 6.5

In plain English

A medium-severity integer overflow in libexpat from libexpat project. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 2% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.1%top 98.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

xmlwf in libexpat before 2.8.2 has an integer overflow for the output filename when -d outputDir is used.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.21expat2.8.2-r0ALPINE-CVE-2026-56409
Alpine:v3.22expat2.8.2-r0ALPINE-CVE-2026-56409
Alpine:v3.23expat2.8.2-r0ALPINE-CVE-2026-56409
Alpine:v3.24expat2.8.2-r0ALPINE-CVE-2026-56409
Debian:12expat2.5.0-1+deb12u3DEBIAN-CVE-2026-56409
Debian:13expat2.8.2-1~deb13u1DEBIAN-CVE-2026-56409
Debian:14expat2.8.2-1DEBIAN-CVE-2026-56409
Ubuntu:22.04:LTScadaverno fix listedUBUNTU-CVE-2026-56409
Ubuntu:24.04:LTScadaverno fix listedUBUNTU-CVE-2026-56409
Ubuntu:25.10cadaverno fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.04:LTScadaverno fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.10cadaverno fix listedUBUNTU-CVE-2026-56409
Ubuntu:22.04:LTSexpat2.4.7-1ubuntu0.9UBUNTU-CVE-2026-56409
Ubuntu:22.04:LTSexpat2.4.7-1ubuntu0.9USN-8813-1
Ubuntu:24.04:LTSexpat2.6.1-2ubuntu0.6UBUNTU-CVE-2026-56409
Ubuntu:24.04:LTSexpat2.6.1-2ubuntu0.6USN-8813-1
Ubuntu:25.10expatno fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.04:LTSexpat2.7.4-1ubuntu0.2UBUNTU-CVE-2026-56409
Ubuntu:26.04:LTSexpat2.7.4-1ubuntu0.2USN-8813-1
Ubuntu:22.04:LTSinsighttoolkit4no fix listedUBUNTU-CVE-2026-56409
Ubuntu:22.04:LTSmatanzano fix listedUBUNTU-CVE-2026-56409
Ubuntu:24.04:LTSmatanzano fix listedUBUNTU-CVE-2026-56409
Ubuntu:25.10matanzano fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.04:LTSmatanzano fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.10matanzano fix listedUBUNTU-CVE-2026-56409
Ubuntu:25.10swish-eno fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.10swish-eno fix listedUBUNTU-CVE-2026-56409
Ubuntu:22.04:LTStdomno fix listedUBUNTU-CVE-2026-56409
Ubuntu:24.04:LTStdomno fix listedUBUNTU-CVE-2026-56409
Ubuntu:25.10tdomno fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.04:LTStdomno fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.10tdomno fix listedUBUNTU-CVE-2026-56409
Ubuntu:22.04:LTSwbxml2no fix listedUBUNTU-CVE-2026-56409
Ubuntu:24.04:LTSwbxml2no fix listedUBUNTU-CVE-2026-56409
Ubuntu:25.10wbxml2no fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.04:LTSwbxml2no fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.10wbxml2no fix listedUBUNTU-CVE-2026-56409
Ubuntu:25.10xmlrpc-cno fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.04:LTSxmlrpc-cno fix listedUBUNTU-CVE-2026-56409
Ubuntu:26.10xmlrpc-cno fix listedUBUNTU-CVE-2026-56409

Affected products (as reported)

VendorProductVersions
libexpat project libexpat 0 – before 2.8.2

Weakness: CWE-190 · Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L

References