UBUNTU-CVE-2026-50737

When applying replicated changes for a row that is missing one or more columns, pglogical evaluates the affected table's default expressions on the subscriber. Because the apply worker runs at a privilege level equivalent to a PostgreSQL superuser in default installations, any function invoked by such a default expression also runs at that privilege. A party acting as the publisher can use this path to cause functions to be executed on the subscriber as superuser, escalating from a role permitted to use pglogical to full superuser. This is a second, independent path to the same superuser escalation tracked under CVE-2026-50736 (the pglogical queue issue). To exploit the issue an attacker must be able to direct a subscription at an endpoint they control. In default installations this requires privileges normally reserved for a superuser, so the issue is most relevant to managed deployments where the ability to create subscriptions has been delegated to non-superuser roles.