From SQLi to RCE - Exploiting LangGraph’s Checkpointer - Check Point Research

From SQLi to RCE – Exploiting LangGraph’s Checkpointer

June 11, 2026

By Yarden Porat

AI agents need memory. Frameworks like LangGraph provide it through checkpointers – persistence layers that store execution state. But what happens when that persistence layer isn’t locked down?

Key Points

Background

LangGraph is an open-source framework for building stateful, multi-agent AI systems with built-in persistence. It’s an extension of LangChain, with over 50 million monthly downloads according to PyPI stats.

Checkpointers are LangGraph’s persistence layer that stores execution state at each step. LangGraph supports two checkpointer implementations: SQLite and PostgreSQL.

Vulnerability #1: SQL Injection (CVE-2025-67644)

The SQLite Checkpointer Database Schema: The SQLite checkpointer uses an internal table called checkpoints with the following structure:

CREATE TABLE checkpoints (
    thread_id TEXT NOT NULL,
    checkpoint_ns TEXT NOT NULL DEFAULT '',
    checkpoint_id TEXT NOT NULL,
    parent_checkpoint_id TEXT,
    type TEXT,
    checkpoint BLOB,
    metadata BLOB,
    PRIMARY KEY (thread_id, checkpoint_ns, checkpoint_id)
);

The metadata column stores additional contextual information about each checkpoint in JSON format. For example:

{
  "user_id": "alice",
  "step": 1,
  "source": "input"
}

The list() Function and Filtering:

When calling the list() function on sqliteSaver (the checkpointer), the filter parameter is used to query checkpoints based on their metadata:

def list(self, config: RunnableConfig | None, *, filter: dict[str, Any] | None = None, before: RunnableConfig | None = None, limit: int | None = None) -> Iterator[CheckpointTuple]:

The filter parameter is passed to an internal function called _metadata_predicate, which constructs the SQL WHERE clause to query checkpoints by their metadata fields.

The Injection

The vulnerability exists in how _metadata_predicate handles the query_key from the filter dictionary. An attacker-controlled filter could provide a query_key with a ' character that will escape the JSON path string and inject arbitrary SQL code.

Injection -> Arbitrary Deserialization

To understand how SQL injection leads to arbitrary deserialization, we need to see the complete picture. Here’s the SQL query that gets executed in list():

query = f"""SELECT thread_id, checkpoint_ns, checkpoint_id, parent_checkpoint_id, type, checkpoint, metadata
FROM checkpoints
{where}
ORDER BY checkpoint_id DESC"""

... this query retrieves checkpoint data from the database, including the checkpoint’s BLOB column.

The Attack

Using SQL injection in the WHERE clause, an attacker can inject a UNION SELECT that adds their own row to the query results:

SELECT thread_id, checkpoint_ns, checkpoint_id, parent_checkpoint_id, type, checkpoint, metadata
FROM checkpoints
WHERE ... (injected: ') UNION SELECT 'thread1', 'ns', 'checkpoint1', NULL, 'msgpack', X'', '{}' -- )

The injected UNION SELECT returns a fake checkpoint row where the checkpoint column contains attacker-controlled serialized data. When the code loops through the query results, it deserializes this malicious checkpoint’s BLOB, giving the attacker arbitrary deserialization.

Vulnerability #2: MsgPack Unsafe Deserialization (CVE-2026-28277)

Now let’s examine what happens during deserialization. The self.serde.loads_typed() function that deserializes checkpoint data looks like this:

def loads_typed(self, data: tuple[str, bytes]) -> Any:

What is msgpack?

MessagePack (msgpack) is a binary serialization format designed to be faster and more compact than JSON. LangGraph uses ormsgpack, a Rust-based implementation with Python bindings.

Msgpack Extensions

MessagePack allows developers to define custom extension types to handle additional data types beyond its built-in primitives.

The vulnerability

If we pass a msgpack with EXT_CONSTRUCTOR_SINGLE_ARG code, and the tuple:

  1. os
  2. system
  3. Command (“echo PWN > /tmp/pwned.txt” for example)

... it will:

  1. Import the os module
  2. Get the system function from it
  3. Call os.system("echo PWN > /tmp/pwned.txt")

This gives an attacker arbitrary code execution.

Vulnerability #3: SQL Injection in the Redis Checkpointer (CVE-2026-27022)

The same injection class affects langgraph-checkpoint-redis: user-controlled keys in the filter dictionary are interpolated directly into the query instead of bound as parameters.

Additional SQL Injection Findings

Beyond the primary SQL injection in the filter parameter, we identified additional defense-in-depth SQL injection issues in both the SQLite and PostgreSQL checkpointers.

Disclosure Timeline

2025-11-19: CVE-2025-67644 (SQL injection), CVE-2026-28227 (msgpack deserialization) And CVE-2026-27022 (Redis injection) disclosed to LangChain team

2025-12-10: CVE-2025-67644 fixed and publicly released in langgraph-checkpoint-sqlite 3.0.1

2026-02-20: CVE-2026-27022 fixed and publicly released in langgraph-checkpoint-redis 1.0.2

2026-03-05: CVE-2026-28277 fixed and publicly released in langgraph-checkpoint 4.0.1

Note on Vendor Response

The LangChain team responded quickly to fix the critical SQL injection vulnerability, which effectively breaks the attack chain described in this research. They continue to work methodically on additional remediation efforts, including the msgpack deserialization issue.