PYSEC-2026-1575

Summary

A critical remote OS command injection vulnerability has been identified in the Llama Factory training process. This vulnerability arises from improper handling of user input, allowing malicious actors to execute arbitrary OS commands on the host system. The issue is caused by insecure usage of the Popen function with shell=True, coupled with unsanitized user input. Immediate remediation is required to mitigate the risk.

Affected Version

Llama Factory versions <=0.9.0 are affected by this vulnerability.

Impact

Exploitation of this vulnerability allows attackers to:

1. Execute arbitrary OS commands on the server.
2. Potentially compromise sensitive data or escalate privileges.
3. Deploy malware or create persistent backdoors in the system.

This significantly increases the risk of data breaches and operational disruption.

Root Cause

The vulnerability originates from the training process where the output_dir value, obtained from the user input, is injected into the popen function without any sanitization. Furthermore, popen is invoked in a unsafe way by enabling the interact shell (shell=True), leading to remote OS command injection vulnerability.

Vulnerable snippet:

# https://github.com/hiyouga/LLaMA-Factory/blob/bd639a137e6f46e1a0005cc91572f5f1ec894f74/src/llamafactory/webui/runner.py#L304-L323
def _launch(self, data: Dict["Component", Any], do_train: bool) -> Generator[Dict["Component", Any], None, None]:
				...
        args = self._parse_train_args(data) if do_train else self._parse_eval_args(data)
				...
        self.trainer = Popen(f"llamafactory-cli train {save_cmd(args)}", env=env, shell=True)
        yield from self.monitor()

Proof of Concept (PoC)

Steps to Reproduce

• Deploy llama factory

• Execute the exploitation script from: https://gist.github.com/superboy-zjc/f2d2b93ae511c445ba97e144b70e534d

  python3 llama-factory-rce.py --url http://127.0.0.1:7861 --cmd "curl XXX" --trace
  

Bad actors are able to execute any OS command as they want.

Remediation Recommendations

Avoid using shell=True in Popen.

• Instead, pass the command and its arguments as a list. This prevents user inputs from being executed as part of a shell command.

cmd = [
    "llamafactory-cli",
    "train", 
  	*save_cmd(args).split(),
]
self.trainer = Popen(cmd, env=env)