diff -u dnsmasq-2.79/debian/changelog dnsmasq-2.79/debian/changelog
--- dnsmasq-2.79/debian/changelog
+++ dnsmasq-2.79/debian/changelog
@@ -1,3 +1,9 @@
+dnsmasq (2.79-1ubuntu0.5) bionic; urgency=medium
+
+  * src/forward.c: add missing EDNS0 section. (LP: #1785383)
+
+ -- Paride Legovini <paride@ubuntu.com>  Fri, 24 Sep 2021 13:05:51 +0200
+
 dnsmasq (2.79-1ubuntu0.4) bionic-security; urgency=medium
 
   * SECURITY UPDATE: fixed port use when specific server is requested
diff -u dnsmasq-2.79/src/forward.c dnsmasq-2.79/src/forward.c
--- dnsmasq-2.79/src/forward.c
+++ dnsmasq-2.79/src/forward.c
@@ -571,6 +571,8 @@
   if (udpfd != -1)
     {
       plen = setup_reply(header, plen, addrp, flags, daemon->local_ttl);
+      if (oph)
+	plen = add_pseudoheader(header, plen, ((unsigned char *) header) + PACKETSZ, daemon->edns_pktsz, 0, NULL, 0, do_bit, 0);
       send_from(udpfd, option_bool(OPT_NOWILD) || option_bool(OPT_CLEVERBIND), (char *)header, plen, udpaddr, dst_addr, dst_iface);
     }
 
@@ -1997,7 +1999,11 @@
 	
 	      /* In case of local answer or no connections made. */
 	      if (m == 0)
-		m = setup_reply(header, (unsigned int)size, addrp, flags, daemon->local_ttl);
+		{
+		  m = setup_reply(header, (unsigned int)size, addrp, flags, daemon->local_ttl);
+		  if (have_pseudoheader)
+		    m = add_pseudoheader(header, m, ((unsigned char *) header) + 65536, daemon->edns_pktsz, 0, NULL, 0, do_bit, 0);
+		}
 	    }
 	}