LangGraph checkpoint savers provide Postgres- and SQLite-backed state persistence for LangGraph workflows and agents. Prior to langgraph-checkpoint-postgres 3.1.3 and langgraph-checkpoint-sqlite 3.1.2, PostgresStore, AsyncPostgresStore, SqliteStore, and AsyncSqliteStore flatten namespace labels with ".".join(namespace), while BaseStore validates labels only for put and aput. Unvalidated dotted labels passed through get, search, delete, list_namespaces, their asynchronous equivalents, or direct batch and abatch operations can resolve to another tenant's stored namespace, allowing cross-namespace reads, overwrites, or deletion. InMemoryStore is not affected because it compares namespace tuples. This issue is fixed in langgraph-checkpoint-postgres 3.1.3 and langgraph-checkpoint-sqlite 3.1.2.

Affected: PyPI: langgraph-checkpoint-postgres, PyPI: langgraph-checkpoint-sqlite

### Summary

The Postgres and SQLite stores save a namespace as its labels joined with `.`, so `("tenant", "bob")` and `("tenant.bob",)` map to the same stored namespace. `put` rejected labels containing `.`, but `get`, `search`, `delete`, `list_namespaces`, their async versions, and ops passed directly to `batch`/`abatch` did not. A caller that could pass such a label could read, overwrite or delete items in another namespace.

### Details

`BaseStore` checked namespace labels only in `put`/`aput`. The other methods passed the namespace on unchecked, and `batch`/`abatch` checked nothing, including the `PutOp` items inside them. `PostgresStore`, `AsyncPostgresStore`, `SqliteStore` and `AsyncSqliteStore` turn a namespace into text with `".".join(namespace)`, so a label containing `.` resolved to the namespace whose labels it spells out:

- `get(("tenant.bob",), key)`, `search(("tenant.bob",))` and `list_namespaces(prefix=("tenant.bob",))` returned data stored under `("tenant", "bob")`. - `delete(("tenant.alice",), key)` deleted the item stored under `("tenant", "alice")`. - `batch([PutOp(("tenant.bob",), key, value)])` overwrote the item stored under `("tenant", "bob")`.

All releases of `langgraph-checkpoint-postgres` before 3.1.3 and `langgraph-checkpoint-sqlite` before 3.1.2 are affected. `InMemoryStore` compares namespaces as tuples and is not affected.

### Impact

You may be affected if you use one of these stores, rely on namespaces to keep users or tenants apart, and…