Unsafe yaml deserialization

Impact

NVFLARE contains a vulnerability in its utils module, where YAML files are loaded via yaml.load() instead of yaml.safe_load(). The deserialization of Untrusted Data, may allow an unprivileged network attacker to cause Remote Code Execution, Denial Of Service, and Impact to both Confidentiality and Integrity.

All versions before 2.1.2 are affected.

CVSS Score = 9.8

[AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H](https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fnvd.nist.gov%2Fvuln-metrics%2Fcvss%2Fv3-calculator%3Fvector%3DAV%3AN%2FAC%3AL%2FPR%3AN%2FUI%3AN%2FS%3AU%2FC%3AH%2FI%3AH%2FA%3AH&data=05%7C01%7Cchesterc%40nvidia.com%7Ce9600bde16854b0b380008da4fc544f7%7C43083d15727340c1b7db39efd9ccc17a%7C0%7C0%7C637910005925574215%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=5kBrXEmAbqp8R31JCH%2FG95MUly72UPVihnBwiRFmvBY%3D&reserved=0)

Patches

The patch will be included in nvflare==2.1.2

Workarounds

Change yaml.load() to yaml.safe_load()

Additional information

Issue Found by: Oliver Sellwood (@Nintorac)