diff -up openssl-1.1.1g/ssl/statem/extensions.c.sig-alg-null-dereference openssl-1.1.1g/ssl/statem/extensions.c
--- openssl-1.1.1g/ssl/statem/extensions.c.sig-alg-null-dereference	2021-03-25 15:04:24.781522476 +0100
+++ openssl-1.1.1g/ssl/statem/extensions.c	2021-03-25 15:04:24.792522584 +0100
@@ -1136,6 +1136,7 @@ static int init_sig_algs(SSL *s, unsigne
     /* Clear any signature algorithms extension received */
     OPENSSL_free(s->s3->tmp.peer_sigalgs);
     s->s3->tmp.peer_sigalgs = NULL;
+    s->s3->tmp.peer_sigalgslen = 0;
 
     return 1;
 }
@@ -1145,6 +1146,7 @@ static int init_sig_algs_cert(SSL *s, un
     /* Clear any signature algorithms extension received */
     OPENSSL_free(s->s3->tmp.peer_cert_sigalgs);
     s->s3->tmp.peer_cert_sigalgs = NULL;
+    s->s3->tmp.peer_cert_sigalgslen = 0;
 
     return 1;
 }
diff -up openssl-1.1.1g/test/recipes/70-test_renegotiation.t.sig-alg-null-dereference openssl-1.1.1g/test/recipes/70-test_renegotiation.t
--- openssl-1.1.1g/test/recipes/70-test_renegotiation.t.sig-alg-null-dereference	2021-03-25 15:59:52.226408743 +0100
+++ openssl-1.1.1g/test/recipes/70-test_renegotiation.t	2021-03-25 16:07:25.528618852 +0100
@@ -38,7 +38,7 @@ my $proxy = TLSProxy::Proxy->new(
 $proxy->clientflags("-no_tls1_3");
 $proxy->reneg(1);
 $proxy->start() or plan skip_all => "Unable to start up Proxy for tests";
-plan tests => 3;
+plan tests => 4;
 ok(TLSProxy::Message->success(), "Basic renegotiation");
 
 #Test 2: Client does not send the Reneg SCSV. Reneg should fail
@@ -77,6 +77,20 @@ SKIP: {
        "Check ClientHello version is the same");
 }
 
+SKIP: {
+    skip "TLSv1.2 disabled", 1
+        if disabled("tls1_2");
+
+    #Test 4: Test for CVE-2021-3449. client_sig_algs instead of sig_algs in
+    #        resumption ClientHello
+    $proxy->clear();
+    $proxy->filter(\&sigalgs_filter);
+    $proxy->clientflags("-tls1_2");
+    $proxy->reneg(1);
+    $proxy->start();
+    ok(TLSProxy::Message->fail(), "client_sig_algs instead of sig_algs");
+}
+
 sub reneg_filter
 {
     my $proxy = shift;
@@ -95,4 +109,24 @@ sub reneg_filter
             $message->repack();
         }
     }
+}
+
+sub sigalgs_filter
+{
+    my $proxy = shift;
+    my $cnt = 0;
+
+    # We're only interested in the second ClientHello message
+    foreach my $message (@{$proxy->message_list}) {
+        if ($message->mt == TLSProxy::Message::MT_CLIENT_HELLO) {
+            next if ($cnt++ == 0);
+
+            my $sigs = pack "C10", 0x00, 0x08,
+                            # rsa_pkcs_sha{256,384,512,1}
+                            0x04, 0x01,  0x05, 0x01,  0x06, 0x01,  0x02, 0x01;
+            $message->set_extension(TLSProxy::Message::EXT_SIG_ALGS_CERT, $sigs);
+            $message->delete_extension(TLSProxy::Message::EXT_SIG_ALGS);
+            $message->repack();
+        }
+    }
 }
diff -up openssl-1.1.1g/util/perl/TLSProxy/Message.pm.sig-alg-null-dereference openssl-1.1.1g/util/perl/TLSProxy/Message.pm
--- openssl-1.1.1g/util/perl/TLSProxy/Message.pm.sig-alg-null-dereference	2021-03-25 15:59:19.648106296 +0100
+++ openssl-1.1.1g/util/perl/TLSProxy/Message.pm	2021-03-25 16:04:25.623947880 +0100
@@ -1,4 +1,4 @@
-# Copyright 2016-2019 The OpenSSL Project Authors. All Rights Reserved.
+# Copyright 2016-2021 The OpenSSL Project Authors. All Rights Reserved.
 #
 # Licensed under the OpenSSL license (the "License").  You may not use
 # this file except in compliance with the License.  You can obtain a copy
@@ -448,7 +448,7 @@ sub ciphersuite
 }
 
 #Update all the underlying records with the modified data from this message
-#Note: Only supports re-encrypting for TLSv1.3
+#Note: Only supports TLSv1.3 and ETM encryption.
 sub repack
 {
     my $self = shift;
@@ -490,15 +490,38 @@ sub repack
         # (If a length override is ever needed to construct invalid packets,
         #  use an explicit override field instead.)
         $rec->decrypt_len(length($rec->decrypt_data));
-        $rec->len($rec->len + length($msgdata) - $old_length);
-        # Only support re-encryption for TLSv1.3.
-        if (TLSProxy::Proxy->is_tls13() && $rec->encrypted()) {
-            #Add content type (1 byte) and 16 tag bytes
-            $rec->data($rec->decrypt_data
-                .pack("C", TLSProxy::Record::RT_HANDSHAKE).("\0"x16));
+		# Only support re-encryption for TLSv1.3 and ETM.
+        if ($rec->encrypted()) {
+            if (TLSProxy::Proxy->is_tls13()) {
+                #Add content type (1 byte) and 16 tag bytes
+                $rec->data($rec->decrypt_data
+                    .pack("C", TLSProxy::Record::RT_HANDSHAKE).("\0"x16));
+            } elsif ($rec->etm()) {
+                my $data = $rec->decrypt_data;
+                #Add padding
+                my $padval = length($data) % 16;
+                $padval = 15 - $padval;
+                for (0..$padval) {
+                    $data .= pack("C", $padval);
+                }
+
+                #Add MAC. Assumed to be 20 bytes
+                foreach my $macval (0..19) {
+                    $data .= pack("C", $macval);
+                }
+
+                if ($rec->version() >= TLSProxy::Record::VERS_TLS_1_1) {
+                    #Explicit IV
+                    $data = ("\0"x16).$data;
+                }
+                $rec->data($data);
+            } else {
+                die "Unsupported encryption: No ETM";
+            }
         } else {
             $rec->data($rec->decrypt_data);
         }
+        $rec->len(length($rec->data));
 
         #Update the fragment len in case we changed it above
         ${$self->message_frag_lens}[0] = length($msgdata)