CVE-2023-39345: Unauthorized Access to Private Fields in User Registration API

System Details

NameValue
OSWindows 11
Version4.11.1 (node v16.14.2)
Databasemysql

Description

I marked some fields as private fields in user content-type, and tried to register as a new user via api, at the same time I added content to fill the private fields and sent a post request, and as you can see from the images below, I can write to the private fields.

To prevent this, I went to the extension area and tried to extend the register method, for this I wanted to do it using the sanitizeInput function that I know in the source codes of the strap. But the sanitizeInput function does not filter out private fields.

 const { auth } = ctx.state;
 const data = ctx.request.body;
 const userSchema = strapi.getModel("plugin::users-permissions.user");

 sanitize.contentAPI.input(data, userSchema, { auth });

here’s the solution I’ve temporarily kept to myself, code snippet

 const body = ctx.request.body;

 const { attributes } = strapi.getModel("plugin::users-permissions.user");

 const sanitizedData = _.omitBy(body, (data, key) => {
  const attribute = attributes[key];

  if (_.isNil(attribute)) {
   return false;
  }

  //? If you want, you can throw an error for fields that we does not expect.

  // if (_.isNil(attribute))
  //  throw new ApplicationError(`Unexpected value ${key}`);

  // if private value is true, we do not want to send it to the database.
  return attribute.private;
 });

 return sanitizedData;

References

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