mcp-server-semgrep/semgrep-rules/javascript/jsonwebtoken/security/audit/jwt-decode-without-verify.yaml

MCP Server for Semgrep Integration - static code analysis with AI

rules:
- id: jwt-decode-without-verify
  message: >-
    Detected the decoding of a JWT token without a verify step.
    JWT tokens must be verified before use, otherwise the token's
    integrity is unknown. This means a malicious actor could forge
    a JWT token with any claims. Call '.verify()' before using the token.
  metadata:
    cwe:
    - 'CWE-345: Insufficient Verification of Data Authenticity'
    owasp:
    - A08:2021 - Software and Data Integrity Failures
    source-rule-url: https://semgrep.dev/blog/2020/hardcoded-secrets-unverified-tokens-and-other-common-jwt-mistakes/
    asvs:
      section: 'V3: Session Management Verification Requirements'
      control_id: 3.5.3 Insecue Stateless Session Tokens
      control_url: https://github.com/OWASP/ASVS/blob/master/4.0/en/0x12-V3-Session-management.md#v35-token-based-session-management
      version: '4'
    category: security
    technology:
    - jwt
    subcategory:
    - audit
    likelihood: LOW
    impact: LOW
    confidence: LOW
    references:
    - https://owasp.org/Top10/A08_2021-Software_and_Data_Integrity_Failures
  languages:
  - javascript
  - typescript
  severity: WARNING
  patterns:
  - pattern-inside: |
      $JWT = require('jsonwebtoken');
      ...
  - pattern-not-inside: | # nosemgrep: slow-pattern-top-ellipsis
      ...
      $JWT.verify($TOKEN, ...)
      ...
  - pattern-not-inside: | # nosemgrep: slow-pattern-top-ellipsis
      ...
      if (<... $JWT.verify($TOKEN, ...) ...>) { ... }
      ...
  - pattern: $JWT.decode($TOKEN, ...)