CVE-2026-56408 is an integer overflow or wraparound vulnerability (CWE-190) in the libexpat project affecting versions prior to 2.8.2. The flaw occurs in the copyString function, potentially allowing an attacker to cause memory corruption or other unintended behavior due to improper handling of integer values. The vulnerability has a CVSS 3.1 base score of 6.9 with the vector AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L, indicating local attack vector, high attack complexity, no privileges required, no user interaction, unchanged scope, and high impact on confidentiality and integrity with low impact on availability. No known exploits are reported in the wild and no vendor advisory or patch information is currently available.

The vulnerability can lead to high confidentiality and integrity impacts, meaning sensitive information could be exposed or altered. Availability impact is low, so denial of service or system crashes are less likely. Exploitation requires local access and high attack complexity, reducing the likelihood of widespread exploitation. No known exploits have been reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, users should consider restricting local access to trusted users only and monitor for updates from the libexpat project. No official patch or workaround is currently documented.