mcp-server-semgrep/semgrep-rules/csharp/dotnet/security/audit/razor-use-of-htmlstring.yaml

MCP Server for Semgrep Integration - static code analysis with AI

rules:
- id: razor-use-of-htmlstring
  message: ASP.NET Core MVC provides an HtmlString class which isn't automatically encoded upon output.
    This should never be used in combination with untrusted input as this will expose an XSS vulnerability.
  severity: WARNING
  metadata:
    likelihood: LOW
    impact: MEDIUM
    confidence: LOW
    category: security
    cwe:
    - 'CWE-116: Improper Encoding or Escaping of Output'
    owasp:
    - A03:2021 - Injection
    references:
    - https://cwe.mitre.org/data/definitions/116.html
    - https://owasp.org/Top10/A03_2021-Injection/
    - https://docs.microsoft.com/en-us/aspnet/core/security/cross-site-scripting?view=aspnetcore-6.0#html-encoding-using-razor
    subcategory:
    - audit
    technology:
    - .net
  languages:
  - generic
  paths:
    include:
    - '*.cshtml'
  patterns:
  - pattern-either:
    - pattern: new ...HtmlString(...)
    - pattern: '@(new ...HtmlString(...))'
  - pattern-not-inside: '@(new ...HtmlString(...HtmlEncode(...)))'
  - pattern-not-inside: '@(new ...HtmlString(...Encode(...)))'
  - pattern-not-inside: new ...HtmlString(...HtmlEncode(...))
  - pattern-not-inside: new ...HtmlString(...Encode(...))