--- /dev/null
+CVE: CVE-2022-43680
+Upstream-Status: Backport [5290462a7ea1278a8d5c0d5b2860d4e244f997e4]
+Signed-off-by: Ross Burton <ross.burton@arm.com>
+
+From 5290462a7ea1278a8d5c0d5b2860d4e244f997e4 Mon Sep 17 00:00:00 2001
+From: Sebastian Pipping <sebastian@pipping.org>
+Date: Tue, 20 Sep 2022 02:44:34 +0200
+Subject: [PATCH] lib: Fix overeager DTD destruction in
+ XML_ExternalEntityParserCreate
+
+---
+ expat/lib/xmlparse.c | 8 ++++++++
+ 1 file changed, 8 insertions(+)
+
+diff --git a/lib/xmlparse.c b/lib/xmlparse.c
+index aacd6e7fc..57bf103cc 100644
+--- a/lib/xmlparse.c
++++ b/lib/xmlparse.c
+@@ -1068,6 +1068,14 @@ parserCreate(const XML_Char *encodingName,
+ parserInit(parser, encodingName);
+
+ if (encodingName && ! parser->m_protocolEncodingName) {
++ if (dtd) {
++ // We need to stop the upcoming call to XML_ParserFree from happily
++ // destroying parser->m_dtd because the DTD is shared with the parent
++ // parser and the only guard that keeps XML_ParserFree from destroying
++ // parser->m_dtd is parser->m_isParamEntity but it will be set to
++ // XML_TRUE only later in XML_ExternalEntityParserCreate (or not at all).
++ parser->m_dtd = NULL;
++ }
+ XML_ParserFree(parser);
+ return NULL;
+ }