diff --git a/configure.ac b/configure.ac
index 43aaa84b7..457843860 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4762,10 +4762,10 @@ else
     fi
     if test "$ENABLED_ASN" = "yes"; then
         AM_CFLAGS="$AM_CFLAGS -DWOLFSSL_ASN_TEMPLATE"
+    elif test "$ENABLED_ASN" = "original"; then
+        AM_CFLAGS="$AM_CFLAGS -DWOLFSSL_ASN_ORIGINAL"
     else
-        if test "$ENABLED_ASN" != "original"; then
-            AC_MSG_ERROR([Invalid asn option. Valid are: template or original. Seen: $ENABLED_ASN.])
-        fi
+        AC_MSG_ERROR([Invalid asn option. Valid are: template or original. Seen: $ENABLED_ASN.])
     fi
 
     # turn off ASN if leanpsk on
diff --git a/tests/suites.c b/tests/suites.c
index 1604e18ea..5c367fe9c 100644
--- a/tests/suites.c
+++ b/tests/suites.c
@@ -1060,7 +1060,9 @@ int SuiteTest(int argc, char** argv)
 #if defined(HAVE_ECC) && !defined(NO_SHA256) && defined(WOLFSSL_CUSTOM_CURVES) && \
     defined(HAVE_ECC_KOBLITZ) && defined(HAVE_ECC_BRAINPOOL) && \
         /* Intel QuickAssist and Cavium Nitrox do not support custom curves */ \
-        !defined(HAVE_INTEL_QA) && !defined(HAVE_CAVIUM_V)
+        !defined(HAVE_INTEL_QA) && !defined(HAVE_CAVIUM_V) && \
+        /* only supported with newer ASN template code */ \
+        defined(WOLFSSL_ASN_TEMPLATE)
 
     /* TLS non-NIST curves (Koblitz / Brainpool) */
     XSTRLCPY(argv0[1], "tests/test-ecc-cust-curves.conf", sizeof(argv0[1]));
diff --git a/wolfcrypt/src/asn.c b/wolfcrypt/src/asn.c
index 16d773c5e..59046cd33 100644
--- a/wolfcrypt/src/asn.c
+++ b/wolfcrypt/src/asn.c
@@ -1210,7 +1210,7 @@ static int GetASN_ObjectId(const byte* input, word32 idx, int length)
     /* Last octet of a sub-identifier has bit 8 clear. Last octet must be last
      * of a subidentifier. Ensure last octet hasn't got top bit set.
      */
-    else if ((input[(int)idx + length - 1] & 0x80) != 0x00) {
+    else if ((input[(int)idx + length - 1] & 0x80) == 0x80) {
         WOLFSSL_MSG("OID last octet has top bit set");
         ret = ASN_PARSE_E;
     }
@@ -2430,6 +2430,19 @@ static int GetASNHeader_ex(const byte* input, byte tag, word32* inOutIdx,
     if ((ret == 0) && (GetLength_ex(input, &idx, &length, maxIdx, check) < 0)) {
         ret = ASN_PARSE_E;
     }
+    if (ret == 0 && tag == ASN_OBJECT_ID) {
+        if (length < 3) {
+            /* OID data must be at least 3 bytes. */
+            WOLFSSL_MSG("OID length less than 3");
+            ret = ASN_PARSE_E;
+        }
+        else if ((input[(int)idx + length - 1] & 0x80) == 0x80) {
+            /* Last octet of a sub-identifier has bit 8 clear. Last octet must be
+            * last of a subidentifier. Ensure last octet hasn't got top bit set. */
+            WOLFSSL_MSG("OID last octet has top bit set");
+            ret = ASN_PARSE_E;
+        }
+    }
     if (ret == 0) {
         /* Return the length of data and index after header. */
         *len      = length;
@@ -2691,14 +2704,15 @@ int GetASNInt(const byte* input, word32* inOutIdx, int* len,
         return ret;
 
     if (*len > 0) {
-
 #ifndef WOLFSSL_ASN_INT_LEAD_0_ANY
         /* check for invalid padding on negative integer.
          * c.f. X.690 (ISO/IEC 8825-2:2003 (E)) 10.4.6; RFC 5280 4.1
          */
         if (*len > 1) {
-            if ((input[*inOutIdx] == 0xff) && (input[*inOutIdx + 1] & 0x80))
-                return ASN_PARSE_E;
+            if ((input[*inOutIdx] == 0xff) && (input[*inOutIdx + 1] & 0x80)) {
+                WOLFSSL_MSG("Bad INTEGER encoding of negative");
+                return ASN_EXPECT_0_E;
+            }
         }
 #endif
 
@@ -2708,8 +2722,10 @@ int GetASNInt(const byte* input, word32* inOutIdx, int* len,
             (*len)--;
 
 #ifndef WOLFSSL_ASN_INT_LEAD_0_ANY
-            if (*len > 0 && (input[*inOutIdx] & 0x80) == 0)
-                return ASN_PARSE_E;
+            if (*len > 0 && (input[*inOutIdx] & 0x80) == 0) {
+                WOLFSSL_MSG("INTEGER is negative");
+                return ASN_EXPECT_0_E;
+            }
 #endif
         }
     }
@@ -3474,7 +3490,7 @@ int CheckBitString(const byte* input, word32* inOutIdx, int* len,
     }
 
     b = input[idx];
-    if (zeroBits && b != 0x00)
+    if (zeroBits && (b != 0x00))
         return ASN_EXPECT_0_E;
     if (b >= 0x08)
         return ASN_PARSE_E;
@@ -6920,7 +6936,7 @@ int ToTraditionalInline_ex2(const byte* input, word32* inOutIdx, word32 sz,
 
     if (tag == ASN_OBJECT_ID) {
         if ((*algId == ECDSAk) && (eccOid != NULL)) {
-            if (GetObjectId(input, &idx, eccOid, oidCurveType, maxIdx) < 0)
+            if (GetObjectId(input, &idx, eccOid, oidCurveType, sz) < 0)
                 return ASN_PARSE_E;
         }
         else {
@@ -11572,9 +11588,11 @@ static int GetCertHeader(DecodedCert* cert)
                                                             cert->sigIndex) < 0)
         return ASN_PARSE_E;
 
-    if (wc_GetSerialNumber(cert->source, &cert->srcIdx, cert->serial,
-                                           &cert->serialSz, cert->sigIndex) < 0)
-        return ASN_PARSE_E;
+    ret = wc_GetSerialNumber(cert->source, &cert->srcIdx, cert->serial,
+        &cert->serialSz, cert->sigIndex);
+    if (ret < 0) {
+        return ret;
+    }
 
     return ret;
 }
@@ -18590,6 +18608,7 @@ static int DecodeAltNames(const byte* input, word32 sz, DecodedCert* cert)
 #ifndef WOLFSSL_ASN_TEMPLATE
     word32 idx = 0;
     int length = 0;
+    word32 numNames = 0;
 
     WOLFSSL_ENTER("DecodeAltNames");
 
@@ -18622,8 +18641,13 @@ static int DecodeAltNames(const byte* input, word32 sz, DecodedCert* cert)
             return BUFFER_E;
         }
 
-        current_byte = input[idx++];
+        numNames++;
+        if (numNames > WOLFSSL_MAX_ALT_NAMES) {
+            WOLFSSL_MSG("\tToo many subject alternative names");
+            return ASN_ALT_NAME_E;
+        }
 
+        current_byte = input[idx++];
         length--;
 
         /* Save DNS Type names in the altNames list. */
@@ -20153,6 +20177,7 @@ static int DecodeSubtree(const byte* input, word32 sz, Base_entry** head,
 #ifndef WOLFSSL_ASN_TEMPLATE
     word32 idx = 0;
     int ret = 0;
+    word32 cnt = 0;
 
     (void)heap;
 
@@ -20161,6 +20186,14 @@ static int DecodeSubtree(const byte* input, word32 sz, Base_entry** head,
         word32 nameIdx;
         byte b, bType;
 
+        if (limit > 0) {
+            cnt++;
+            if (cnt > limit) {
+                WOLFSSL_MSG("too many name constraints");
+                return ASN_NAME_INVALID_E;
+            }
+        }
+
         if (GetSequence(input, &idx, &seqLength, sz) < 0) {
             WOLFSSL_MSG("\tfail: should be a SEQUENCE");
             return ASN_PARSE_E;
diff --git a/wolfcrypt/test/test.c b/wolfcrypt/test/test.c
index 6f47de0fb..c9e10ae5d 100644
--- a/wolfcrypt/test/test.c
+++ b/wolfcrypt/test/test.c
@@ -18078,7 +18078,7 @@ WOLFSSL_TEST_SUBROUTINE wc_test_ret_t memory_test(void)
 #endif
     static const char* certBadOid =
             CERT_ROOT "test" CERT_PATH_SEP "cert-bad-oid.der";
-#ifndef WOLFSSL_NO_ASN_STRICT
+#if defined(WOLFSSL_ASN_TEMPLATE) && !defined(WOLFSSL_NO_ASN_STRICT)
     static const char* certBadUtf8 =
             CERT_ROOT "test" CERT_PATH_SEP "cert-bad-utf8.der";
 #endif
@@ -18383,7 +18383,7 @@ static wc_test_ret_t cert_bad_asn1_test(void)
         /* Subject name OID: 55 04 f4. Last byte with top bit set invalid. */
         ret = cert_load_bad(certBadOid, tmp, ASN_PARSE_E);
     }
-#ifndef WOLFSSL_NO_ASN_STRICT
+#if defined(WOLFSSL_ASN_TEMPLATE) && !defined(WOLFSSL_NO_ASN_STRICT)
     if (ret == 0) {
         /* Issuer name UTF8STRING: df 52 4e 44. Top bit of second byte not set.
          */