Properly initialize all fields of a SSL object after allocation.

Misc/NEWS

@@ -15,6 +15,8 @@ Core and Builtins
 Library
 -------
 
+- Properly initialize all fields of a SSL object after allocation.
+
 - Issue #19095: SSLSocket.getpeercert() now raises ValueError when the
   SSL handshake hasn't been done.
 

Modules/_ssl.c

@@ -486,6 +486,7 @@ newPySSLSocket(PySSLContext *sslctx, PySocketSockObject *sock,
     self->ssl = NULL;
     self->Socket = NULL;
     self->ctx = sslctx;
+    self->shutdown_seen_zero = 0;
     self->handshake_done = 0;
     Py_INCREF(sslctx);