diff --git a/src/lib/gssapi/spnego/spnego_mech.c b/src/lib/gssapi/spnego/spnego_mech.c
index 832abe6..4384708 100644
--- a/src/lib/gssapi/spnego/spnego_mech.c
+++ b/src/lib/gssapi/spnego/spnego_mech.c
@@ -54,8 +54,8 @@ typedef const gss_OID_desc *gss_OID_const;
 
 /* der routines defined in libgss */
 extern unsigned int gssint_der_length_size(OM_uint32);
-extern int gssint_get_der_length(unsigned char **, OM_uint32, OM_uint32*);
-extern int gssint_put_der_length(OM_uint32, unsigned char **, OM_uint32);
+extern int gssint_get_der_length(unsigned char **, OM_uint32, unsigned int*);
+extern int gssint_put_der_length(OM_uint32, unsigned char **, unsigned int);
 
 
 /* private routines for spnego_mechanism */
@@ -1249,7 +1249,8 @@ spnego_gss_accept_sec_context(void *ct,
 	}
 cleanup:
 	if (return_token != NO_TOKEN_SEND && return_token != CHECK_MIC) {
-		tmpret = make_spnego_tokenTarg_msg(negState, sc->internal_mech,
+		tmpret = make_spnego_tokenTarg_msg(negState,
+						   sc ? sc->internal_mech : GSS_C_NO_OID,
 						   &mechtok_out, mic_out,
 						   return_token,
 						   output_token);
@@ -1802,22 +1803,16 @@ static gss_buffer_t
 get_input_token(unsigned char **buff_in, unsigned int buff_length)
 {
 	gss_buffer_t input_token;
-	unsigned int bytes;
+	unsigned int len;
 
-	if (**buff_in != OCTET_STRING)
+	if (g_get_tag_and_length(buff_in, OCTET_STRING, buff_length, &len) < 0)
 		return (NULL);
 
-	(*buff_in)++;
 	input_token = (gss_buffer_t)malloc(sizeof (gss_buffer_desc));
-
 	if (input_token == NULL)
 		return (NULL);
 
-	input_token->length = gssint_get_der_length(buff_in, buff_length, &bytes);
-	if ((int)input_token->length == -1) {
-		free(input_token);
-		return (NULL);
-	}
+	input_token->length = len;
 	input_token->value = malloc(input_token->length);
 
 	if (input_token->value == NULL) {
@@ -1869,8 +1864,8 @@ get_mech_set(OM_uint32 *minor_status, unsigned char **buff_in,
 {
 	gss_OID_set returned_mechSet;
 	OM_uint32 major_status;
-	OM_uint32 length;
-	OM_uint32 bytes;
+	int length;
+	unsigned int bytes;
 	OM_uint32 set_length;
 	unsigned char		*start;
 	int i;
@@ -1882,22 +1877,25 @@ get_mech_set(OM_uint32 *minor_status, unsigned char **buff_in,
 	(*buff_in)++;
 
 	length = gssint_get_der_length(buff_in, buff_length, &bytes);
+	if (length < 0 || buff_length - bytes < (unsigned int)length)
+		return NULL;
 
 	major_status = gss_create_empty_oid_set(minor_status,
 						&returned_mechSet);
 	if (major_status != GSS_S_COMPLETE)
 		return (NULL);
 
-	for (set_length = 0, i = 0; set_length < length; i++) {
+	for (set_length = 0, i = 0; set_length < (unsigned int)length; i++) {
 		gss_OID_desc *temp = get_mech_oid(minor_status, buff_in,
 			buff_length - (*buff_in - start));
-		if (temp != NULL) {
-		    major_status = gss_add_oid_set_member(minor_status,
-					temp, &returned_mechSet);
-		    if (major_status == GSS_S_COMPLETE) {
+		if (temp == NULL)
+			break;
+
+		major_status = gss_add_oid_set_member(minor_status,
+						      temp, &returned_mechSet);
+		if (major_status == GSS_S_COMPLETE) {
 			set_length += returned_mechSet->elements[i].length +2;
 			generic_gss_release_oid(minor_status, &temp);
-		    }
 		}
 	}
 
@@ -2097,7 +2095,7 @@ get_negTokenResp(OM_uint32 *minor_status,
 		return GSS_S_DEFECTIVE_TOKEN;
 	if (*ptr++ == SEQUENCE) {
 		tmplen = gssint_get_der_length(&ptr, REMAIN, &bytes);
-		if (tmplen < 0)
+		if (tmplen < 0 || REMAIN < (unsigned int)tmplen)
 			return GSS_S_DEFECTIVE_TOKEN;
 	}
 	if (REMAIN < 1)
@@ -2107,7 +2105,7 @@ get_negTokenResp(OM_uint32 *minor_status,
 
 	if (tag == CONTEXT) {
 		tmplen = gssint_get_der_length(&ptr, REMAIN, &bytes);
-		if (tmplen < 0)
+		if (tmplen < 0 || REMAIN < (unsigned int)tmplen)
 			return GSS_S_DEFECTIVE_TOKEN;
 
 		if (g_get_tag_and_length(&ptr, ENUMERATED,
@@ -2128,7 +2126,7 @@ get_negTokenResp(OM_uint32 *minor_status,
 	}
 	if (tag == (CONTEXT | 0x01)) {
 		tmplen = gssint_get_der_length(&ptr, REMAIN, &bytes);
-		if (tmplen < 0)
+		if (tmplen < 0 || REMAIN < (unsigned int)tmplen)
 			return GSS_S_DEFECTIVE_TOKEN;
 
 		*supportedMech = get_mech_oid(minor_status, &ptr, REMAIN);
@@ -2142,7 +2140,7 @@ get_negTokenResp(OM_uint32 *minor_status,
 	}
 	if (tag == (CONTEXT | 0x02)) {
 		tmplen = gssint_get_der_length(&ptr, REMAIN, &bytes);
-		if (tmplen < 0)
+		if (tmplen < 0 || REMAIN < (unsigned int)tmplen)
 			return GSS_S_DEFECTIVE_TOKEN;
 
 		*responseToken = get_input_token(&ptr, REMAIN);
@@ -2156,7 +2154,7 @@ get_negTokenResp(OM_uint32 *minor_status,
 	}
 	if (tag == (CONTEXT | 0x03)) {
 		tmplen = gssint_get_der_length(&ptr, REMAIN, &bytes);
-		if (tmplen < 0)
+		if (tmplen < 0 || REMAIN < (unsigned int)tmplen)
 			return GSS_S_DEFECTIVE_TOKEN;
 
 		*mechListMIC = get_input_token(&ptr, REMAIN);
@@ -2464,6 +2462,8 @@ make_spnego_tokenTarg_msg(OM_uint32 status, gss_OID mech_wanted,
 
 	if (outbuf == GSS_C_NO_BUFFER)
 		return (GSS_S_DEFECTIVE_TOKEN);
+	if (sendtoken == INIT_TOKEN_SEND && mech_wanted == GSS_C_NO_OID)
+	    return (GSS_S_DEFECTIVE_TOKEN);
 
 	outbuf->length = 0;
 	outbuf->value = NULL;
@@ -2715,7 +2715,7 @@ g_get_tag_and_length(unsigned char **buf, int tag,
 						&encoded_len);
 		if (tmplen < 0) {
 			ret = -1;
-		} else if (tmplen > buflen - (ptr - *buf)) {
+		} else if ((unsigned int)tmplen > buflen - (ptr - *buf)) {
 			ret = -1;
 		} else
 			ret = 0;
diff --git a/src/lib/krb5/asn.1/asn1buf.c b/src/lib/krb5/asn.1/asn1buf.c
index 8baac24..587cccc 100644
--- a/src/lib/krb5/asn.1/asn1buf.c
+++ b/src/lib/krb5/asn.1/asn1buf.c
@@ -78,11 +78,11 @@ asn1_error_code asn1buf_wrap_data(asn1buf *buf, const krb5_data *code)
 
 asn1_error_code asn1buf_imbed(asn1buf *subbuf, const asn1buf *buf, const unsigned int length, const int indef)
 {
+  if (buf->next > buf->bound + 1) return ASN1_OVERRUN;
   subbuf->base = subbuf->next = buf->next;
   if (!indef) {
+      if (length > (size_t)(buf->bound + 1 - buf->next)) return ASN1_OVERRUN;
       subbuf->bound = subbuf->base + length - 1;
-      if (subbuf->bound > buf->bound)
-	  return ASN1_OVERRUN;
   } else /* constructed indefinite */
       subbuf->bound = buf->bound;
   return 0;
@@ -200,6 +200,7 @@ asn1_error_code asn1buf_remove_octetstring(asn1buf *buf, const unsigned int len,
 {
   int i;
 
+  if (buf->next > buf->bound + 1) return ASN1_OVERRUN;
   if (len > buf->bound + 1 - buf->next) return ASN1_OVERRUN;
   if (len == 0) {
       *s = 0;
@@ -218,6 +219,7 @@ asn1_error_code asn1buf_remove_charstring(asn1buf *buf, const unsigned int len,
 {
   int i;
 
+  if (buf->next > buf->bound + 1) return ASN1_OVERRUN;
   if (len > buf->bound + 1 - buf->next) return ASN1_OVERRUN;
   if (len == 0) {
       *s = 0;