Unsanitized user input in deserialization method


Deserializing data from untrusted sources, like user inputs or request parameters, without proper verification is a security risk. Attackers can embed malicious code or payloads within serialized data. When your application deserializes this data without checks, it becomes vulnerable to attacks.


  • Do not deserialize data from untrusted sources directly. This can lead to security vulnerabilities.
  • Do validate and sanitize all data before deserializing it. Ensure that the data is coming from a trusted source and is in the expected format.
  • Do use data formats that are purely data-oriented and not tied to a specific programming language, such as JSON or XML, for serialization and deserialization. This approach minimizes the risk of executing malicious code during deserialization.
  • Do use recommended safer alternatives wherever possible. For example, instead of PyYAML's load function, use the safe_load function which limits results to simple Python objects like integers or lists.
      yaml.safe_load(some_input) # safer alternative to PyYAML load 


Associated CWE

OWASP Top 10


To skip this rule during a scan, use the following flag

bearer scan /path/to/your-project/ --skip-rule=python_lang_deserialization_of_user_input

To run only this rule during a scan, use the following flag

bearer scan /path/to/your-project/ --only-rule=python_lang_deserialization_of_user_input