CVE-2025-58367 is a critical vulnerability in the Python DeepDiff library's Delta class that allows class pollution via its constructor. This flaw can be exploited to modify the internal allow list for safe deserialization, enabling insecure Pickle deserialization and potentially arbitrary code execution. The vulnerability also allows denial of service by corrupting built-in classes and may lead to other impacts such as authentication bypass in web applications. The issue affects DeepDiff versions from 5.0.0 up to but not including 8.6.1, with a fix released in version 8.6.1.