CVE-2026-78699: rename_tenant returns :ok on a failed rename, enabling cross-tenant access in AshPostgres

Severity: high (CVSS 7.2 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-30 · updated 2026-09-01
Weakness: CWE-252

Description

Unchecked Return Value vulnerability in ash-project ash_postgres allows a user who can drive a tenant rename to a name that collides with an existing tenant's schema to have their tenant record repointed at that other tenant's live schema, gaining access to its data. AshPostgres.MultiTenancy.rename_tenant/3 issues the ALTER SCHEMA ... RENAME TO ... with the non-raising Ecto.Adapters.SQL.query/2, discards its {:ok, _} | {:error, _} result, and unconditionally returns :ok. PostgreSQL rejects the rename when the target schema already exists (and on insufficient privilege or lock timeout), but that failure never reaches the caller. The calling manage_tenant update action therefore sees success and commits the tenant row with the new name, which is the schema of a different existing tenant, so subsequent reads and writes for that tenant run against the other tenant's data. This issue affects ash_postgres: from 0.25.0 before 2.13.0.

Affected products

ash-project ash_postgres: from 0.25.0 before 2.13.0 — fixed in 2.13.0

How to fix

Upgrade to a fixed version: ash-project ash_postgres 2.13.0. Check the vendor advisory for mitigations.

References

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