There is a HIGH severity vulnerability
affecting CPython.

When an Expat parser with a registered ElementDeclHandler parses an inline
document type definition containing a deeply nested content model a C stack
overflow occurs.

Please see the linked CVE ID for the latest information on
affected versions:

* https://www.cve.org/CVERecord?id=CVE-2026-4224
* https://github.com/python/cpython/commit/eb0e8be3a7e11b87d198a2c3af1ed0eccf532768