diff --git a/src/libopensc/pkcs15-oberthur.c b/src/libopensc/pkcs15-oberthur.c
index d3236a98..bf88a06a 100644
--- a/src/libopensc/pkcs15-oberthur.c
+++ b/src/libopensc/pkcs15-oberthur.c
@@ -884,12 +884,16 @@ sc_pkcs15emu_oberthur_add_data(struct sc_pkcs15_card *p15card,
 	offs = 2;
 
 	/* Label */
-	if (offs > info_len) {
+	if (offs + 2 > info_len) {
 		free(info_blob);
 		LOG_TEST_RET(ctx, SC_ERROR_UNKNOWN_DATA_RECEIVED, "Failed to add data: no 'label'");
 	}
 	label = info_blob + offs + 2;
 	label_len = *(info_blob + offs + 1) + *(info_blob + offs) * 0x100;
+	if (offs + 2 + label_len > info_len) {
+		free(info_blob);
+		LOG_TEST_RET(ctx, SC_ERROR_UNKNOWN_DATA_RECEIVED, "Invalid length of 'label' received");
+	}
 	if (label_len > sizeof(dobj.label) - 1)
 		label_len = sizeof(dobj.label) - 1;
 	offs += 2 + *(info_blob + offs + 1);
@@ -906,7 +910,7 @@ sc_pkcs15emu_oberthur_add_data(struct sc_pkcs15_card *p15card,
 	offs += 2 + app_len;
 
 	/* OID encode like DER(ASN.1(oid)) */
-	if (offs > info_len) {
+	if (offs + 1 > info_len) {
 		free(info_blob);
 		LOG_TEST_RET(ctx, SC_ERROR_UNKNOWN_DATA_RECEIVED, "Failed to add data: no 'OID'");
 	}