mcp-server-semgrep/semgrep-rules/python/lang/security/deserialization/avoid-pyyaml-load.yaml

MCP Server for Semgrep Integration - static code analysis with AI

rules:
- id: avoid-pyyaml-load
  metadata:
    owasp:
    - A08:2017 - Insecure Deserialization
    - A08:2021 - Software and Data Integrity Failures
    cwe:
    - 'CWE-502: Deserialization of Untrusted Data'
    references:
    - https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation
    - https://nvd.nist.gov/vuln/detail/CVE-2017-18342
    category: security
    technology:
    - pyyaml
    cwe2022-top25: true
    cwe2021-top25: true
    subcategory:
    - audit
    likelihood: LOW
    impact: MEDIUM
    confidence: MEDIUM
  languages:
  - python
  message: >-
    Detected a possible YAML deserialization vulnerability. `yaml.unsafe_load`, `yaml.Loader`,
    `yaml.CLoader`, and `yaml.UnsafeLoader` are all known to be unsafe methods of deserializing YAML.
    An attacker with control over the YAML input could create special YAML input that allows the attacker
    to run arbitrary Python code. This would allow the attacker to steal files, download and install malware,
    or otherwise take over the machine. Use `yaml.safe_load` or `yaml.SafeLoader` instead.
  fix-regex:
    regex: unsafe_load
    replacement: safe_load
    count: 1
  severity: ERROR
  patterns:
  - pattern-inside: |
      import yaml
      ...
  - pattern-not-inside: |
      $YAML = ruamel.yaml.YAML(...)
      ...
  - pattern-either:
    - pattern: yaml.unsafe_load(...)
    - pattern: yaml.load(..., Loader=yaml.Loader, ...)
    - pattern: yaml.load(..., Loader=yaml.UnsafeLoader, ...)
    - pattern: yaml.load(..., Loader=yaml.CLoader, ...)
    - pattern: yaml.load_all(..., Loader=yaml.Loader, ...)
    - pattern: yaml.load_all(..., Loader=yaml.UnsafeLoader, ...)
    - pattern: yaml.load_all(..., Loader=yaml.CLoader, ...)