Affected: langchain-ai langgraph, langchain-ai langgraph-checkpoint-sqlite, langchain-ai langgraph-checkpoint-postgres

LangGraph Checkpoint Postgres and SQLite Checkpoint are the Postgres and SQLite implementations of LangGraph's checkpoint saver. Prior to 3.1.1, the langgraph-checkpoint-postgres and langgraph-checkpoint-sqlite packages persisted hierarchical namespaces as a dot joined string and scoped reads by matching that string as a simple prefix pattern, so a read scoped to one namespace could also match a sibling namespace whose flattened form shares the same leading characters, or a namespace label containing unescaped pattern metacharacters, allowing an authenticated caller to retrieve stored items belonging to another tenant or user through an ordinary scoped search or list namespaces call, with no crafted input required. This issue is fixed in versions 3.1.1 of langgraph-checkpoint-postgres and langgraph-checkpoint-sqlite.

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

## Summary

The Postgres and SQLite stores persist hierarchical namespaces as a dot-joined string (`("memories", "alice")` becomes `memories.alice`) and scoped reads by matching that string with `LIKE '<path>%'`. Because `LIKE` has no notion of the `.` separator, a scoped `search` or `list_namespaces` also matched sibling namespaces whose flattened form shares leading characters.

Applications commonly use the namespace as a tenant boundary. Where they do, a read scoped to one namespace could return items belonging to another, without any crafted input — an ordinary scoped request was sufficient.

We have no evidence of this behavior being exploited in the wild.

## Affected users / systems

You may be affected if you:

- use `PostgresStore`/`AsyncPostgresStore` or `SqliteStore`/`AsyncSqliteStore`, and - rely on the namespace to separate data between users or tenants, and - have namespace labels where one is a prefix of another (`1` and `12`, `alice` and `alice2`), or labels containing `_` or `%`

Applications whose namespace labels are fixed-length identifiers such as UUIDs, containing no `_` or `%`, are not affected — no such label can be a prefix of another. `InMemoryStore` compares namespaces element-wise and is not affected.

Three distinct cases were possible:

- **Sibling namespaces.** A read scoped to `("foo",)` also returned items under `("foobar",)` and `("foo2",)`. - **Unescaped pattern metacharacters.** `_` and `%` are legal namespace labels — only `.` is rejecte…