<!-- If you're new to Python and you're not sure whether what you're experiencing is a bug, the CPython issue tracker is not the right place to seek help. Consider the following options instead: - reading the Python tutorial: https://docs.python.org/3/tutorial/ - posting in the "Users" category on discuss.python.org: https://discuss.python.org/c/users/7 - emailing the Python-list mailing list: https://mail.python.org/mailman/listinfo/python-list - searching our issue tracker (https://github.com/python/cpython/issues) to see if your problem has already been reported --> **Bug report** The following code should raise `binascii.Error` but does not: ```python import binascii binascii.a2b_base64(b'=aa==') ``` It appears (from looking at the source code) that this is also the case in 3.11, even in strict mode. **Your environment** <!-- Include as many relevant details as possible about the environment you experienced the bug in --> - CPython versions tested on: 3.10 - Operating system and architecture: Fedora 36, Linux 5.15.52, x86_64