CVE-2025-66455 LMDeploy has Remote Code Execution by Pickle Deserialization via handle_zmq_recv in lmdeploy/lmdeploy/pytorch/disagg/conn/engine_conn.py
Unauthenticated attackers can achieve remote code execution on LMDeploy DistServe servers by sending malicious pickle payloads via ZeroMQ.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2025-66455?
CVE-2025-66455 is a critical unsafe deserialization vulnerability in InternLM lmdeploy, published on 18 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
LMDeploy is a toolkit for compressing, deploying, and serving large language models. Starting in version 0.9.2 and prior to version 0.16.0, LMDeploy's PyTorch DistServe/PD-disaggregation control plane used `recv_pyobj()` to deserialize messages received through a ZeroMQ PULL socket. PyZMQ implements `recv_pyobj()` using Python pickle deserialization, which can execute arbitrary code while reconstructing an object. The peer address used by the receiver was supplied through the `POST /distserve/p2p_connect` HTTP endpoint. An attacker who could reach an affected DistServe API server could cause the server to connect to an attacker-controlled ZeroMQ endpoint and deserialize a crafted pickle payload. API-key authentication is not enabled unless the operator explicitly configures it. As a result, affected DistServe deployments without API keys allowed unauthenticated remote code execution with the privileges of the LMDeploy serving process. This issue affects the PyTorch backend when PD-disaggregation/DistServe is enabled. Ordinary deployments that do not use the affected disaggregated-serving path do not expose this data flow. The fix was released in LMDeploy 0.16.0. Users who cannot upgrade immediately should prevent untrusted clients from reaching `/distserve/*` endpoints, restrict the DistServe HTTP and ZeroMQ control planes to trusted cluster networks, configure API-key authentication, and block arbitrary outbound ZeroMQ connections from serving nodes. These measures reduce exposure but do not make pickle deserialization safe.
Weakness: CWE-502
Which versions are affected by CVE-2025-66455?
3 open source packages ship an affected version, including lmdeploy.
| Package | Affected | Fixed in |
|---|---|---|
lmdeploy PyPI | From 0.9.2 | 0.16.0 |
lmdeploy PyPI | From 0.9.2 | 0.16.0 |
lmdeploy PyPI | From 0.9.2 | 0.16.0 |
How do I fix CVE-2025-66455?
Upgrade lmdeploy to 0.16.0 or later.
Upgrade, and only deserialise data from trusted sources or with an allow-list of types. More about Unsafe deserialization.
Is CVE-2025-66455 being exploited?
There is no known exploitation of CVE-2025-66455 in the wild and no public exploit code.
Sources
Also known as GHSA-2vh9-42vm-xmv2, PYSEC-2026-4077.