gh-160040: Add ssl eMudhra distrust entry to whatsnew [3.11]

Signed-off-by: Christian Heimes <christian@python.org>

Author: tiran

Doc/whatsnew/3.11.rst

@@ -2820,3 +2820,18 @@ tarfile
   :func:`~tarfile.TarFile.errorlevel` is zero.
   (Contributed by Matt Prodani and Petr Viktorin in :gh:`112887`
   and CVE 2025-4435.)
+
+
+Notable changes in 3.11.18
+==========================
+
+ssl
+---
+
+* The :mod:`ssl` module now rejects TLS certificate chains that contain one
+  of a set of compromised eMudhra intermediate CA certificates.  The affected
+  certificates are identified by their public key, so cross-signed copies that
+  reuse the same key are blocked as well.  It is a defense-in-depth backstop
+  that applies even when an application supplies its own root CA bundle, and
+  regardless of whether the platform trust store has removed trust.
+  (Contributed by Christian Heimes in :gh:`160040` for CVE 2026-115557.)