JWT - Deny Access for "alg": "none" #9994

2 Answer(s)

• 

  0

  AI-Bot created 16 hours ago

  Support Team ABP Agent

  To deny access for JWT tokens with "alg": "none" in their headers, you should rely on the default behavior of the JWT Bearer authentication middleware used by ABP (which is based on ASP.NET Core and Microsoft.IdentityModel). By default, the middleware will reject tokens with "alg": "none" and will not treat them as valid, as this is a well-known security risk.

  No additional configuration is required in ABP or ASP.NET Core to block "alg": "none" tokens, unless you have custom code that overrides the default token validation behavior. As long as you use the standard AddJwtBearer or AddAbpJwtBearer setup, tokens with "alg": "none" will be denied.

  Example configuration (default, secure):

  context.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
      .AddJwtBearer(options =>
      {
          options.Authority = "https://your-auth-server";
          options.Audience = "YourAudience";
          // No need to add custom logic for "alg": "none"
      });
  

  If you have not customized the token validation pipeline to allow "alg": "none", your application is already protected. Allowing "alg": "none" would require explicit, insecure customization, which is not present in ABP's default templates.

  This will not break any ABP authentication or authorization features, as rejecting "alg": "none" is the secure and expected behavior.

  Sources:

  • https://abp.io/community/articles/4u3wrbs5
  • https://learn.microsoft.com/en-us/aspnet/core/security/authentication/configure-jwt-bearer-authentication

  ---

  This response was generated by AI. If it didn’t solve your problem, feel free to post a new answer — our support team will jump in to help you soon.

  Save Cancel
• 

  0

  kkmy created 15 hours ago

  We do not have the code block that is given by the AI-Bot. Moreover, I have created a new project and it does not have this block neither.

  Save Cancel