CVE-2025-64439 LangGraph Checkpoint affected by RCE in "json" mode of JsonPlusSerializer
Attackers can achieve remote code execution by exploiting unsafe deserialization in the JsonPlusSerializer when the system falls back to JSON mode.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-64439?
CVE-2025-64439 is a high-severity unsafe deserialization vulnerability in langchain-ai langgraph, published on 7 Nov 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
LangGraph SQLite Checkpoint is an implementation of LangGraph CheckpointSaver that uses SQLite DB (both sync and async, via aiosqlite). In versions 2.1.2 and below, the 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. By 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. This issue is fixed in version 3.0.0.
Weakness: CWE-502
Which versions are affected by CVE-2025-64439?
3 open source packages ship an affected version, including langgraph-checkpoint.
| Package | Affected | Fixed in |
|---|---|---|
langgraph-checkpoint PyPI | All versions | 3.0.0 |
langgraph-checkpoint PyPI | All versions | 3.0.0 |
langgraph-checkpoint PyPI | All versions | 3.0.0 |
How do I fix CVE-2025-64439?
Upgrade langgraph-checkpoint to 3.0.0 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2025-64439 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-64439 exists.
Sources
Also known as CLSA-2026-1779670109, GHSA-wwqv-p2pp-99h5, PYSEC-2026-1527, ROOT-APP-PYPI-CVE-2025-64439.