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.

The pglogical queue mechanism, used to convey out-of-band commands such as replicated DDL from a publisher to a subscriber, executes message payloads on the subscriber at the privilege level of the apply worker, which is equivalent to a PostgreSQL superuser in default installations. A party acting as the publisher can send crafted queue messages that cause arbitrary SQL to be executed on the subscriber as superuser, escalating from a role permitted to use pglogical to full superuser and breaking the isolation between tenants in shared deployments. 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.

pglogical's apply worker does not sufficiently validate the length of certain fields in incoming replication protocol messages before copying them, resulting in an out-of-bounds read. A party acting as the publisher for a subscription, for example a non-PostgreSQL endpoint that speaks the pglogical replication protocol, can return crafted messages that cause the subscriber's apply worker to read beyond the bounds of an allocated buffer, disclosing adjacent process memory or crashing the worker. 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.