CVE-2015-10082: Improper Restriction of XML External Entity Reference (CWE-611)
value: A vulnerability classified as problematic has been found in UIKit0 libplist 1.12. This affects the function plist_from_xml of the file src/xplist.c of the component XML Handler. The manipulation leads to xml external entity reference. The patch is named c086cb139af7c82845f6d565e636073ff4b37440. It is recommended to apply a patch to fix this issue. The associated identifier of this vulnerability is VDB-221499.
CWE description: The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.
CVSS v3 base score: 9.8
Published: 2023-02-21T07:15Z
Repository: https://github.com/UIKit0/libplist
Language: C
Files changed: src/xplist.c
Commit date: 2015-01-23 14:56:59 +0100
Commit message: xplist: Fix limited but possible XXE security vulnerability with XML plists

By using a specifically crafted XML file an attacker could use plistutil
to issue a GET request to an arbitrary URL or disclose a local file.
The crafted XML file would be using a custom DTD with an external entity
reference pointing to the file. Practical abuse is limited but let's still
fix it nevertheless. Related to CVE-2013-0339 for libxml2 and CWE-827.
Reported by Loïc Bénis from calypt.com. Thanks!

Diff: diff --git a/src/xplist.c b/src/xplist.c
index 4c106aa..2e86ee5 100644
--- a/src/xplist.c
+++ b/src/xplist.c
@@ -27,10 +27,11 @@
 #include <time.h>
 
 #include <inttypes.h>
 #include <locale.h>
 
+#include <libxml/xmlIO.h>
 #include <libxml/parser.h>
 #include <libxml/tree.h>
 
 #include <node.h>
 #include <node_list.h>
@@ -553,13 +554,24 @@ PLIST_API void plist_to_xml(plist_t plist, char **plist_xml, uint32_t * length)
         setlocale(LC_NUMERIC, saved_locale);
         free(saved_locale);
     }
 }
 
+static xmlParserInputPtr plist_xml_external_entity_loader(const char *URL, const char *ID, xmlParserCtxtPtr ctxt)
+{
+    return NULL;
+}
+
 PLIST_API void plist_from_xml(const char *plist_xml, uint32_t length, plist_t * plist)
 {
-    xmlDocPtr plist_doc = xmlParseMemory(plist_xml, length);
-    xmlNodePtr root_node = xmlDocGetRootElement(plist_doc);
+    /* CVE-2013-0339: disable external entity loading to prevent XXE vulnerability */
+    xmlSetExternalEntityLoader(plist_xml_external_entity_loader);
 
-    xml_to_node(root_node, plist);
-    xmlFreeDoc(plist_doc);
+    /* read XML from memory and disable network access for security reasons */
+    xmlDocPtr plist_doc = xmlReadMemory(plist_xml, length, "plist_from_xml:memory", NULL, XML_PARSE_NONET);
+    if (plist_doc) {
+        xmlNodePtr root_node = xmlDocGetRootElement(plist_doc);
+
+        xml_to_node(root_node, plist);
+        xmlFreeDoc(plist_doc);
+    }
 }

Vulnerable code:     xmlDocPtr plist_doc = xmlParseMemory(plist_xml, length);
    xmlNodePtr root_node = xmlDocGetRootElement(plist_doc);
    xml_to_node(root_node, plist);
    xmlFreeDoc(plist_doc);
Fixed code: #include <libxml/xmlIO.h>
static xmlParserInputPtr plist_xml_external_entity_loader(const char *URL, const char *ID, xmlParserCtxtPtr ctxt)
{
    return NULL;
}

    /* CVE-2013-0339: disable external entity loading to prevent XXE vulnerability */
    xmlSetExternalEntityLoader(plist_xml_external_entity_loader);
    /* read XML from memory and disable network access for security reasons */
    xmlDocPtr plist_doc = xmlReadMemory(plist_xml, length, "plist_from_xml:memory", NULL, XML_PARSE_NONET);
    if (plist_doc) {
        xmlNodePtr root_node = xmlDocGetRootElement(plist_doc);

        xml_to_node(root_node, plist);
        xmlFreeDoc(plist_doc);
    }