Improper Input Validation
In PyYAML before 5.1b1, the `yaml.load()` API could execute arbitrary code if used with untrusted data. The `load()` function was deprecated and the 'UnsafeLoader' was introduced for backward compatibility with the function. NOTE: There was an initial fix which was later reverted. The actual fix occurred in the commit "857dff15".
CWE-20 - Improper Input Validation
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.