You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.
cas-base was reported malicious
OSV:MAL-2025-193014 - Malicious code in cas-base (PyPI)

cas-base
1.5.3

This version was deleted from PyPI around 2026-05-11. Installing fails with:
$ pip3 install cas-base==1.5.3 ERROR: Could not find a version that satisfies the requirement cas-base==1.5.3
View other deleted versions of cas-base

Install through StableBuild

You can install this package from StableBuild's PyPI snapshots from before the version was deleted:
pip3 install \ -i https://YOUR_API_KEY.pypimirror.stablebuild.com/2026-05-10/ \ cas-base==1.5.3
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Or, download files manually

And install manually via pip:
cas_base-1.5.3-py3-none-any.whl (18.7KB)
cas_base-1.5.3.tar.gz (15.1KB)