CVE-2026-96560 in LightLLM
Summary
by MITRE • 09/23/2026
LightLLM through 1.2.0 contains a remote code execution vulnerability in the KV-transfer worker when started with --pd_trans_mode nccl, which exposes an unauthenticated RPyC control channel that deserializes attacker-supplied data. Attackers can send malicious pickled objects to the exposed RPyC ThreadedServer to execute arbitrary code with the privileges of the LightLLM service account.
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Analysis
by VulDB Data Team • 09/23/2026
LightLLM versions through 1.2.0 contain a critical remote code execution vulnerability within its KV-transfer worker component, specifically triggered when the system is configured with the --pd_trans_mode nccl parameter. This configuration exposes an unauthenticated Remote Python Call (RPyC) control channel that fails to implement adequate access controls or input validation mechanisms. The core technical flaw lies in the deserialization of data received through this exposed endpoint without sufficient sanitization, allowing attackers to inject maliciously crafted serialized objects into the system's execution pipeline.
The vulnerability stems from the inherent risks associated with Python’s pickle module and similar serialization libraries, which can execute arbitrary code during the unmarshaling process if they contain specially constructed payloads. When an attacker sends a malicious pickled object to the exposed RPyC ThreadedServer, the server processes this data without verifying its integrity or origin. This lack of authentication combined with unsafe deserialization creates a direct path for exploitation, as the system blindly trusts and executes code embedded within the serialized payload.
Operationally, this vulnerability allows an unauthenticated remote attacker to achieve arbitrary code execution on the affected host. The severity is compounded by the fact that the executed code runs with the privileges of the LightLLM service account. Depending on how the service is deployed, this could grant attackers significant control over the underlying operating system, potentially leading to full compromise of the server, data exfiltration, or use as a pivot point for further attacks within the network infrastructure. The exposure of an unauthenticated channel significantly lowers the barrier to entry for exploitation, making it accessible even to adversaries with limited technical sophistication who can interact with the exposed port over the network.
To mitigate this risk, organizations running LightLLM should immediately upgrade to version 1.2.1 or later where these access controls and validation mechanisms have been addressed. For environments that cannot be patched immediately, it is crucial to restrict network access to the RPyC control channel using firewall rules or security groups, ensuring that only trusted internal services can communicate with this port. Additionally, running LightLLM under a restricted user account with minimal privileges can help limit the potential impact of successful exploitation by reducing the permissions available to any code executed via the vulnerability.
This incident aligns with CWE-502, which describes deserialization of untrusted data as a common cause of injection vulnerabilities and remote code execution. It also maps to MITRE ATT&CK technique T1648, specifically the LEVANTION component related to server-side request forgery or exploitation of service endpoints that handle external inputs without proper validation. Security teams should audit their deployment configurations for any instances where --pd_trans_mode nccl is enabled and ensure strict network segmentation policies are in place to protect these internal communication channels from unauthorized access.