# CVE-2026-48775: LangChain LangGraph unsafe deserialization in JsonPlusSerializer

Source: https://junglewise.ai/threats/cve-2026-48775-langchain-langgraph-unsafe-deserialization-in-jsonplusserializer  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-16. Updated: 2026-06-25  
License: CC BY 4.0 with a link back

CVE-2026-48775 · Severity: medium · CVSS 6.8 · Published 2026-06-16

LangGraph is a library used to build stateful multi-agent applications with LLMs. A vulnerability in how it handles saved application states (checkpoints) could allow an attacker with write access to the database or storage layer to execute malicious code. This could lead to a full takeover of the application worker process and exposure of sensitive runtime secrets.

Technologies: [langgraph-checkpoint (PyPI)](https://junglewise.ai/threats/technologies/pypi-langgraph-checkpoint). Vendors: [LangChain](https://junglewise.ai/threats/vendors/langchain), [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-48775 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-48775 being exploited in the wild.

**How severe is CVE-2026-48775?** Medium severity, with a CVSS score of 6.8, published 16 June 2026.

**Which products and versions are affected?** LangChain Langgraph-Checkpoint < 4.1.1, <= 4.1.0; langgraph-checkpoint (PyPI) ECOSYSTEM:introduced=0,fixed=4.1.1.

**Is there a fix for CVE-2026-48775?** Yes. langgraph-checkpoint (PyPI): upgrade to 4.1.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-48775 attacked?** It is attacked from the adjacent network, in a software library.

**Am I affected by CVE-2026-48775?** Check whether you run LangChain Langgraph-Checkpoint or langgraph-checkpoint (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- langgraph-checkpoint (PyPI): upgrade to 4.1.1 or later

  ```sh
  pip install "langgraph-checkpoint>=4.1.1"
  ```


## Technical details

The vulnerability exists in the `JsonPlusSerializer` component of LangGraph, which is used by default in persistent checkpointers like `PostgresSaver` and `SqliteSaver`. The serializer's deserialization path (CWE-502) could be manipulated to reconstruct arbitrary Python objects (CWE-913) from JSON payloads. An attacker who gains write access to the backing checkpoint store can inject malicious payloads that trigger arbitrary code execution when the application loads or resumes a checkpoint. The fix in version 4.1.1 restricts object reconstruction to a narrow set of safe default constructors.

## Affected products

- langchain-ai langgraph-checkpoint < 4.1.1

## Identifiers

- CVE-2026-48775
- GHSA-fjqc-hq36-qh5p
- PYSEC-2026-2573

## Timeline

- 2026-05-22: disclosed
- 2026-06-16: advisory: NVD publication date
- 2026-06-25: patched: GitHub Advisory reviewed and updated

## References

- [https://api.github.com/users/pucagit](https://api.github.com/users/pucagit)
- [https://github.com/pucagit](https://github.com/pucagit)
- [https://api.github.com/users/pucagit/gists%7B/gist_id%7D](https://api.github.com/users/pucagit/gists%7B/gist_id%7D)
- [https://api.github.com/users/pucagit/repos](https://api.github.com/users/pucagit/repos)
- [https://avatars.githubusercontent.com/u/93117777?v=4](https://avatars.githubusercontent.com/u/93117777?v=4)
- [https://api.github.com/users/pucagit/events%7B/privacy%7D](https://api.github.com/users/pucagit/events%7B/privacy%7D)

## Related threats

- [PYSEC-2026-2574 - LangGraph: BaseCache Deserialization of Untrusted Data may lead to Remote Code Execution](https://junglewise.ai/threats/cve-2026-27794-langgraph-basecache-deserialization-of-untrusted-data-may-lead-to)
- [PYSEC-2026-1527 - LangGraph Checkpoint affected by RCE in "json" mode of JsonPlusSerializer](https://junglewise.ai/threats/cve-2025-64439-langgraph-checkpoint-affected-by-rce-in-json-mode-of)