urlapi: skip appending NULL pointer query

Reported-by: kirbyn17 on hackerone
Closes #12240

diff --git a/lib/urlapi.c b/lib/urlapi.c
index be27b02332419cf7e0a1570bf4be5e5635285d61..329f80393b75ea2e79834bd21f8f628ef37dcfd3 100644 (file)
--- a/lib/urlapi.c
+++ b/lib/urlapi.c
@@ -1902,7 +1902,7 @@ CURLUcode curl_url_set(CURLU *u, CURLUPart what,
     }
     newp = Curl_dyn_ptr(&enc);
 
-    if(appendquery) {
+    if(appendquery && newp) {
       /* Append the 'newp' string onto the old query. Add a '&' separator if
          none is present at the end of the existing query already */