During Xenstore live update the state record for a Xenstore watch with specified watch depth is written with two bytes missing. (CVE-2026-79607)

The vulnerability occurs during the Xenstore live update process. Specifically, the state record for a Xenstore watch that has a specified watch depth is written incorrectly with two bytes missing. When the new Xenstore instance reads this incomplete state record, it encounters an inconsistent state. This inconsistency can cause the Xenstore service to crash or return incorrect data, impacting the availability and reliability of the Xenstore service. The CVSS v3.1 base score is 5.5, indicating a medium severity issue with local attack vector, low attack complexity, requiring low privileges, no user interaction, unchanged scope, and no confidentiality or integrity impact but with availability impact.

The vulnerability can cause Xenstore to crash or provide incorrect data due to inconsistent state records after a live update. This impacts the availability of the Xenstore service but does not affect confidentiality or integrity of data. The attack requires local access with low privileges and does not require user interaction.

No patch or official fix information is provided in the available data. Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, cautious handling of Xenstore live updates and monitoring for crashes or data inconsistencies is advised.