Auth bypass in Ash-Project Ash Postgres

CVE-2026-115627

Incorrect Authorization vulnerability in ash-project ash_postgres allows a user to load destination records linked to a source record only through another tenant's join rows. When a many_to_many relationship, or a through relationship, is loaded with a lateral join (for example with a per-record limit or sort), AshPostgres.DataLayer builds the query for the join resource, and for each resource along a through path, in lateral_join_query/3 and through_step_queries/4 without running that resource's read action, which is where attribute multitenancy is applied. When those resources use strategy :attribute multitenancy, rows belonging to other tenants were joined, so the load returned destination records that the caller's tenant is not related to. This issue affects ash_postgres: from 0.38.0 before 2.15.2.

Vulnerability class: Broken Access Control

Published 2026-10-25.