如果您在使用AWS CloudFormation创建S3存储桶时遇到凭证输出和CORS不起作用的问题，可以尝试以下解决方法：

1. 确认您的CloudFormation模板中是否正确配置了S3存储桶的CORS规则。您可以使用以下示例代码作为参考：

"Resources": {
  "S3Bucket": {
    "Type": "AWS::S3::Bucket",
    "Properties": {
      "BucketName": "your-bucket-name",
      "CorsConfiguration": {
        "CorsRules": [
          {
            "AllowedOrigins": ["*"],
            "AllowedMethods": ["GET", "PUT", "POST", "DELETE", "HEAD"],
            "AllowedHeaders": ["*"]
          }
        ]
      }
    }
  }
}

注意替换your-bucket-name为您自己的存储桶名称。

2. 确认您是否在CloudFormation模板中正确配置了凭证输出。您可以使用以下示例代码作为参考：

"Outputs": {
  "BucketArn": {
    "Description": "S3 Bucket ARN",
    "Value": {"Fn::GetAtt": ["S3Bucket", "Arn"]}
  },
  "BucketName": {
    "Description": "S3 Bucket Name",
    "Value": {"Ref": "S3Bucket"}
  }
}

这将输出S3存储桶的ARN和名称供其他资源使用。

3. 确认您是否正确配置了用于创建S3存储桶的IAM角色。您可以使用以下示例代码作为参考：

"Resources": {
  "S3Bucket": {
    "Type": "AWS::S3::Bucket",
    "Properties": {
      "BucketName": "your-bucket-name",
      "CorsConfiguration": {
        "CorsRules": [
          {
            "AllowedOrigins": ["*"],
            "AllowedMethods": ["GET", "PUT", "POST", "DELETE", "HEAD"],
            "AllowedHeaders": ["*"]
          }
        ]
      },
      "Tags": [
        {
          "Key": "Name",
          "Value": "your-bucket-name"
        }
      ]
    },
    "DeletionPolicy": "Retain",
    "UpdateReplacePolicy": "Retain"
  },
  "BucketPolicy": {
    "Type": "AWS::S3::BucketPolicy",
    "Properties": {
      "Bucket": {"Ref": "S3Bucket"},
      "PolicyDocument": {
        "Statement": [
          {
            "Effect": "Allow",
            "Principal": "*",
            "Action": ["s3:GetObject"],
            "Resource": {"Fn::Join": ["", ["arn:aws:s3:::", {"Ref": "S3Bucket"}, "/*"]]}
          }
        ]
      }
    }
  },
  "BucketPolicyToLambdaRole": {
    "Type": "AWS::IAM::Policy",
    "Properties": {
      "PolicyName": "BucketPolicy",
      "PolicyDocument": {
        "Statement": [
          {
            "Effect": "Allow",
            "Action": "s3:GetObject",
            "Resource": {"Fn::Join": ["", ["arn:aws:s3:::", {"Ref": "S3Bucket"}, "/*"]]}
          }
        ]
      },
      "Roles": [{"Ref": "LambdaRole"}]
    }
  },
  "LambdaRole": {
    "Type": "AWS::IAM::Role",
    "Properties": {
      "AssumeRolePolicyDocument": {
        "Statement": [
          {
            "Effect": "Allow",
            "Principal": {
              "Service": ["lambda.amazonaws.com"]
            },
            "Action": ["sts:AssumeRole"]
          }
        ]
      },
      "Path": "/",
      "Policies": [
        {
          "PolicyName": "S3Access",
          "PolicyDocument": {
            "Statement": [
              {
                "Effect": "Allow",
                "Action": ["s3:GetObject"],
                "Resource": {"Fn::Join": ["", ["arn:aws:s3:::", {"Ref": "S3Bucket"}, "/*"]]}
              }
            ]
          }
        }
      ]
    }
  }
}

这些代码示例显示了如何正确配置S3存储桶的CORS规则、标签、策略和IAM角色。

请注意，这只是一个示例，您需要根据自己的需求