Is my CNN model overfitting?
Your train/validation loss curves are a classic example of overfitting.
It looks like you have 1425 data samples to train a model with &gt; 28 million parameters.
I would suggest trying any/all of the follow:

use a smaller model -&gt; less parameters means less complexity and less ability to overfit
data augmentation -&gt; more data samples means more variation in the dataset for the model to capture
early-stopping -&gt; use something like the Keras callback, which will stop the model training once the validation loss doesn't decrease for a number of epochs

If you happen to be using image data, you might take a look at the Keras ImageDataGenerator, which can do things like flip/rotate your images.