CVE-2026-56407 is an integer overflow vulnerability in the libexpat XML parsing library, specifically in the doProlog function related to storeEntityValue and the entity textLen parameter. This overflow can cause memory corruption or unexpected behavior, potentially impacting confidentiality and integrity of the application using libexpat. The vulnerability affects versions before 2.8.2. No official remediation level or patch information is currently available from the vendor. The CVSS 3.1 base score is 6.9, reflecting a medium severity with 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.

Successful exploitation of this integer overflow could lead to unauthorized disclosure or modification of data (confidentiality and integrity impacts). Availability impact is low. The vulnerability requires local access and has a high attack complexity, reducing the likelihood of exploitation. No known exploits are reported in the wild at this time.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since no official fix or remediation level is provided, users should monitor libexpat project communications for updates. Until a patch is available, consider limiting local access to vulnerable systems and applying any available workarounds recommended by the vendor once released.