Fix CVE-2018-14647:
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2018-14647
https://bugs.python.org/issue34623

Taken from upstream:
https://github.com/python/cpython/commit/f7666e828cc3d5873136473ea36ba2013d624fa1

diff --git Include/pyexpat.h Include/pyexpat.h
index 44259bf6d7..07020b5dc9 100644
--- Include/pyexpat.h
+++ Include/pyexpat.h
@@ -3,7 +3,7 @@
 
 /* note: you must import expat.h before importing this module! */
 
-#define PyExpat_CAPI_MAGIC  "pyexpat.expat_CAPI 1.0"
+#define PyExpat_CAPI_MAGIC  "pyexpat.expat_CAPI 1.1"
 #define PyExpat_CAPSULE_NAME "pyexpat.expat_CAPI"
 
 struct PyExpat_CAPI
@@ -48,6 +48,8 @@ struct PyExpat_CAPI
     enum XML_Status (*SetEncoding)(XML_Parser parser, const XML_Char *encoding);
     int (*DefaultUnknownEncodingHandler)(
         void *encodingHandlerData, const XML_Char *name, XML_Encoding *info);
+    /* might be none for expat < 2.1.0 */
+    int (*SetHashSalt)(XML_Parser parser, unsigned long hash_salt);
     /* always add new stuff to the end! */
 };
 
diff --git Modules/_elementtree.c Modules/_elementtree.c
index 707ab2912b..53f05f937f 100644
--- Modules/_elementtree.c
+++ Modules/_elementtree.c
@@ -3261,6 +3261,11 @@ _elementtree_XMLParser___init___impl(XMLParserObject *self, PyObject *html,
         PyErr_NoMemory();
         return -1;
     }
+    /* expat < 2.1.0 has no XML_SetHashSalt() */
+    if (EXPAT(SetHashSalt) != NULL) {
+        EXPAT(SetHashSalt)(self->parser,
+                           (unsigned long)_Py_HashSecret.expat.hashsalt);
+    }
 
     if (target) {
         Py_INCREF(target);
diff --git Modules/pyexpat.c Modules/pyexpat.c
index 47c3e86c20..aa21d93c11 100644
--- Modules/pyexpat.c
+++ Modules/pyexpat.c
@@ -1887,6 +1887,11 @@ MODULE_INITFUNC(void)
     capi.SetStartDoctypeDeclHandler = XML_SetStartDoctypeDeclHandler;
     capi.SetEncoding = XML_SetEncoding;
     capi.DefaultUnknownEncodingHandler = PyUnknownEncodingHandler;
+#if XML_COMBINED_VERSION >= 20100
+    capi.SetHashSalt = XML_SetHashSalt;
+#else
+    capi.SetHashSalt = NULL;
+#endif
 
     /* export using capsule */
     capi_object = PyCapsule_New(&capi, PyExpat_CAPSULE_NAME, NULL);
b8d0e0720a'>gnu</a>/<a href='/guix/log/gnu/tests?id=d54faf155aeeeb2aceb5cc19f141c2b8d0e0720a'>tests</a>/<a href='/guix/log/gnu/tests/install.scm?id=d54faf155aeeeb2aceb5cc19f141c2b8d0e0720a'>install.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/tests/install.scm?id=d54faf155aeeeb2aceb5cc19f141c2b8d0e0720a&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-05-06 17:12:45 +0200'>2023-05-06</span></td><td><a href='/guix/commit/gnu/tests/install.scm?id=f51888272558d98cf5c196b93fb6c499056fbf6c'>tests: Add missing module imports for marionette-evaluated code.</a><span class='msg-avail'>...<span class='msg-tooltip'>This missing imports became apparent with commit
a09c7da8f8d8e732f969cf0a09aaa78f87032ab1, which runs the marionette
service in a fresh Guile process with fewer imports.

* gnu/tests/databases.scm (run-postgresql-test, run-timescaledb-test)
(run-mysql-test): Add missing module imports for code passed to
'marionette-eval'.
* gnu/tests/docker.scm (run-docker-test, run-docker-system-test): Likewise.
* gnu/tests/mail.scm (run-dovecot-test, run-getmail-test): Likewise.
* gnu/tests/monitoring.scm (run-zabbix-server-test): Likewise.
* gnu/tests/pam.scm (run-test-pam-limits): Likewise.
* gnu/tests/reconfigure.scm (run-switch-to-system-test)
(run-install-bootloader-test): Likewise.
* gnu/tests/security-token.scm (run-pcscd-test): Likewise.
* gnu/tests/install.scm (gui-test-program): Likewise.
* gnu/tests/telephony.scm (run-jami-test): Add modules to
the #:imported-modules argument of 'marionette-operating-system'.
[test]: Remove them from 'with-imported-modules'; remove
'with-extensions'.  Add "d-bus tooling loaded" test to set up %load-path
and %load-compiled-path so the marionette process can find
guile-ac-d-bus and guile-packrat.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-04-21 16:16:38 +0200'>2023-04-21</span></td><td><a href='/guix/commit/gnu/tests/install.scm?id=fb32e226ce3d3cd9bf12989850b2dd719266d583'>tests: Use the client 'start-service' procedure.</a><span class='msg-avail'>...<span class='msg-tooltip'>The previous code worked "by chance": 'start' from (shepherd service)
happened to be in scope because the marionette REPL is created by a mere
'primitive-fork', and 'start' happened to kinda work.

* gnu/tests/base.scm (run-basic-test): Use 'start-service' from (gnu
services herd), not 'start' from (shepherd service), which is not
supposed to work.
* gnu/tests/install.scm (run-install): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-12-05 11:21:18 -0500'>2022-12-05</span></td><td><a href='/guix/commit/gnu/tests/install.scm?id=4016e01fdfe69694cd525c33c80bda53f8c5c4e5'>Revert "tests: install: Fix iso-image-installer test."</a><span class='msg-avail'>...<span class='msg-tooltip'>This reverts commit 0f66ef9aa99d2043abccbc80d858bdeca57534ac.  e2fsprogs is
now included in the installation operating system since
34f69bc6e6ea555929ecca83ee7592f5261ff5f2, making this workaround obsolete.

Suggested-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Maxim Cournoyer</td></tr>