CVE-2026-42812

In Apache Iceberg, the table's metadata files are control files: they tell readers which data files belong to the table and which table version to read.

write.metadata.path is an optional table property that tells Polaris where to write those metadata files. For a table already registered in a Polaris-managed catalog, changing only that property through an ALTER TABLE-style settings change (not a row-level INSERT, SELECT, UPDATE, or DELETE) bypasses the commit-time branch that is supposed to revalidate storage locations.

The full persisted / credential-vending variant requires the affected catalog to have polaris.config.allow.unstructured.table.location=true, with allowedLocations broad enough to include the attacker-chosen target.

allowedLocations is the admin-configured allowlist of storage paths that the catalog is allowed to use. Public project materials suggest that this flag is a real supported compatibility / layout mode, not just a contrived lab-only prerequisite.

In that configuration, a user who can change table settings can cause Apache Polaris itself to write new table metadata to an attacker-chosen reachable storage location before the intended location-validation branch runs.

If the later concrete-path validation also accepts that location, Polaris persists the resulting metadata path into stored table state. Later table-load and credential APIs can then return temporary cloud-storage credentials for the same location without revalidating it. In plain terms, Polaris can later hand out temporary storage access for the same attacker-chosen area.

That attacker-chosen area does not need to be limited to the poisoned table's own files. If it is a broader storage prefix, another table's prefix, or, depending on configuration or provider behavior, even a bucket/container root, the resulting disclosure or corruption scope can extend to any data and metadata Polaris can reach there.

The practical consequences are therefore...